Method of forming color images and apparatus used therefor

ABSTRACT

A method of forming a color image comprising providing a first peelable transfer layer 12 on an electrophotographic light-sensitive element 11 whose surface has releasability, forming one or more color toner images 3 on the first transfer layer by a conventional electrophotographic process, further forming a second transfer layer 13 on the toner images 3, and transferring the toner images 3 together with the first transfer layer 12 and the second transfer layer 13 to a receiving material 16 is disclosed. The method is excellent in transferability of toner image and provides simply and stably color images of high accuracy and high quality without color shear. The transfer layer has good releasability from an electrophotographic light-sensitive element and good adhesion to a receiving material. A color duplicate formed has good retouching property, sealing property and storage stability.

TECHNICAL FIELD

The present invention relates to a method of forming a color image andan apparatus used therefor such as an electrophotographic colorduplicator, a color printer, a color proofer or a color checker.

TECHNICAL BACKGROUND

Methods of forming color printings, color duplicates or color proofs(proofs for printing) which comprises conducting development withelectrophotographic developing agents to form a plurality ofover-lapping color toner images directly on the surface ofelectrophotographic light-sensitive element and transferring theresulting color images at once onto a receiving material such asprinting paper have hitherto been known.

The developing methods include a so-called dry type developing methodand wet type developing method. Color images obtained by the wet typedeveloping method are preferred because of little color shear and goodresolution as compared with those formed with dry toners. However, it isvery difficult to directly transfer wet type toner images entirely fromthe surface of the light-sensitive element to printing paper.

In order to solve this problem, a transfer technique in which anon-aqueous solvent is supplied between a light-sensitive element and areceiving material and then transfer is electrostatically performed isdescribed in JP-A-2-272469 (the term "JP-A" as used herein means an"unexamined published Japanese patent application").

Also, a method in which a transparent film is first laminated on thesurface of a light-sensitive element, wet type toner images are formedby an electrophotographic process on the film, and then the film bearingthe toner images is separated from the light-sensitive element and stuckon paper, thereby forming transferred images is described inJP-A-2-115865 and JP-A-2-115866. According to the method, the film to belaminated has suitably a thickness of 9 μm. However, the production andhandling of a film having such thickness is very troublesome and it isnecessary to arrange a special system for them.

Further, in JP-B-2-43185 (the term "JP-B" as used herein means an"examined Japanese patent publication"), a method in which imagewiseexposure through a transparent electrophotographic light-sensitiveelement and development are conducted repeatedly to form over-lappingcolor separation images on a dielectric support releasably provided onthe light-sensitive element and the dielectric support bearing theimages is transferred to a receiving material is described. Since theimagewise exposure is performed from the side of substrate for thelight-sensitive element according to this method, the substrate isrequired to be transparent. This is disadvantageous in view of a cost.

On the other hand, an electrophotographic transfer method using aso-called dry type developing method in which a releasable transferlayer is provided on the surface of a light-sensitive element, tonerimages are formed on the transfer layer and the toner images aretransferred together with the transfer layer to printing paper isdescribed in JP-A-1-112264, JP-A-1-281464 and JP-A-3-11347.

Moreover, in EP-A-0534479, a method in which a transfer layer is formedon the surface of light-sensitive element which has releasability, oneor more color toner images are formed on the transfer layer by anelectrophotographic process and then the toner images are transferredtogether with the transfer layer onto a receiving material is described.However, a latitude of conditions on the transfer (for example, heatingtemperature, pressure and transportation speed) of toner images togetherwith the transfer layer is still narrow and unsatisfactory in thismethod.

In order to obtain good color images by a color image-forming method inwhich toner images are transferred together with the transfer layer toprinting paper various kinds of requirements must be satisfied.

First, it is important that the transfer layer should be uniformlyprovided in order to perform uniform charging and exposure to light andnot degrade electrophotographic characteristics of anelectrophotographic light-sensitive element since toner images areformed upon an electrophotographic process. Also, the transfer layer isdesired to have good releasability from an electrophotographiclight-sensitive element and good adhesion to a receiving material inorder to conduct easy transfer in the transfer step. Particularly, anenlarged latitude of transfer conditions (for example, heatingtemperature, pressure and transportation speed) is required. Moreover,it is desired that a color duplicate obtained accept retouching andsealing without causing any trouble and have good storage stability, forexample, in that the transfer layer is not peeled off when the colorduplicate has been filed between plastic sheets and piled up.

However, these characteristics have not been fully considered in thetechniques hitherto known and image forming performance of color image,transferability of transfer layer and retouching property, sealingproperty and storage stability of color duplicate are not satisfactorilygood.

The present invention is to solve the above-described various problemsassociated with conventionally known methods of formingelectrophotographic transfer images.

An object of the present invention is to provide a method of forming anelectrophotographic color image which is excellent in transferability oftoner image, which provides simply and stably color images of highaccuracy and high quality without color shear, in which a transfer layerhas good releasability from an electrophotographic light-sensitiveelement and good adhesion to a receiving material, and a color duplicateformed by which method has good retouching property, sealing propertyand storage stability, and an apparatus used therefor.

Another object of the present invention is to provide a method offorming a color image in which a transfer layer is formed by anapparatus of a simple structure in an electrophotographic apparatus anda light-sensitive element is repeatedly usable, thereby reducing arunning cost.

DISCLOSURE OF THE INVENTION

It has been found that the above described objects of the presentinvention are accomplished by a method of forming a color imagecomprising forming at least one color toner image by anelectrophotographic process on a first peelable transfer layer providedon the surface of an electrophotographic light-sensitive element whosesurface has releasability, forming a second transfer layer on the tonerimage and transferring the toner image together with the first transferlayer and the second transfer layer onto a receiving material.

Specifically, the method of forming a color image according to thepresent invention comprises, as shown in FIG. 1 which is a schematicview of the process of the present invention, providing a first peelabletransfer layer (X) 12 on the surface of an electrophotographiclight-sensitive element 11 having at least a support 1 and alight-sensitive layer 2, forming at least one color toner image 3 on thefirst peelable transfer layer by a conventional electrophotographicprocess, forming further a second transfer layer (Y) 13 on the tonerimage, and then transferring the toner image 3 together with thetransfer layer (X) 12 and the transfer layer (Y) 13 onto anothersubstrate (receiving material) 16, thereby providing a color duplicate.

According to the hitherto known methods, toner images are formed on atransfer layer provided on a light-sensitive element and transferredtogether with the transfer layer onto a receiving material. Therefore,in order to obtain a duplicate of excellent color image, the transferlayer is required to satisfy various kinds of condition in that thetransfer layer does not adversely affect electrophotographiccharacteristics in the electrophotographic process, in that it has goodtransferability (i.e., good releasability from a light-sensitive elementand good adhesion to a receiving material) in the transfer step and inthat it has good retouching and sealing properties and filing aptitudeas the resulting color duplicate as described above.

On the contrary, the above-described various requirements for thetransfer layer can be fulfilled by dividing a transfer layer into twolayers (X and Y) before and after the formation of toner image, morespecifically by providing the transfer layer (Y) on the first transferlayer (X) bearing toner images according to the method of the presentinvention to share these requirements with each other depending on itsfunction.

Since the toner image is sandwiched between the transfer layer (X) andthe transfer layer (Y) in the present invention, fixing strength oftoner image is reinforced by the transfer layer, and thus the toner canbe employed without taking its fixing property into carefulconsideration.

It is preferred in the present invention that both the first transferlayer (X) and the second transfer layer (Y) are mainly composed of athermoplastic resin (A) having a glass transition point of not more than140° C. or a softening point of not more than 180° C. in order tofurther improve transferability of the transfer layers.

It is important for the transfer layer (X) used in the present inventionto have features in that it does not degrade electrophotographiccharacteristics (such as chargeability, dark charge retention rate andphotosensitivity) until toner images are formed by anelectrophotographic process, in that it has thermoplasticity sufficientfor easy release from the surface of light-sensitive element in the heattransfer process and in that it accepts retouching and sealing withoutcausing any trouble as the resulting color duplicate which has goodstorage stability wherein the transfer layer is not peeled from thereceiving material when the duplicate has been filed between plasticsheets and piled up during storage.

On the other hand, it is important for the transfer layer (Y) to havegood adhesion not only to toner images and the transfer layer (X) in thenon-image areas but also to a receiving material and to be easilytransferred onto a receiving material in the heat transfer processirrespective of the kind of receiving material. Particularly, goodadhesion of the transfer layer (X) onto a receiving material is veryimportant in order to accelerate the release at the interface betweenthe transfer layer (X) and the light-sensitive element. The transferlayer (Y) does not have any restriction on the electrophotographiccharacteristics, since it is provided after the formation of tonerimage.

The first transfer layer (X) and second transfer layer (Y) arepreferably so constructed as to fulfill the above-described requirementsfor the transfer layer in the present invention.

In particular, in the method according to the present invention whereintransfer layer (Y) is further provided on toner images formed on thesurface of transfer layer (X), excellent transferability of transferlayer can be achieved by employing transfer layer (Y) which has goodadhesion to a receiving material in comparison with a case of conductingtransfer without the formation of transfer layer (Y).

Moreover, a stratiform structure composed of a first transfer layer (X)containing a thermoplastic resin (AH) having a glass transition point offrom 10° C. to 140° C. or a softening point of from 35° C. to 180° C.provided on the surface of light-sensitive element and a second transferlayer (Y). containing a thermoplastic resin (AL) having a glasstransition point of not more than 45° C. or a softening point of notmore than 60° C. which is to adhere to a receiving material is preferredin the present invention. By adopting such a configuration,transferability of the transfer layer to a receiving material isremarkably improved, a further enlarged latitude of transfer conditions(e.g., heating temperature, pressure, and transportation speed) can beachieved, and the transfer can be easily performed irrespective of thekind of receiving material to form a color duplicate. Moreover, theabove-described filing aptitude is more improved since the surface ofthe transfer layer transferred onto a receiving material is composed ofthe thermoplastic resin (AH) having a high glass transition point orsoftening point, and the retouching property and sealing propertysimilar to those of normal paper may be imparted to the resulting colorduplicate by appropriately selecting the thermoplastic resin (AH).

Furthermore, by introducing a polymer component (F) containing at leastone of a silicon atom and a fluorine atom (hereinafter referred to as asilicon atom and/or fluorine atom-containing polymer ,component (F)sometimes) as a copolymer component into the thermoplastic resins (AH)and/or (AL), an effect for further increasing releasability of theresins themselves is obtained.

On the other hand, an adhesive strength of the surface of an-electrophotographic light-sensitive element employed in the presentinvention which surface is to be come into contact with the transferlayer measured according to JIS Z 0237-1980 "Testing methods of pressuresensitive adhesive tapes and sheets" is preferably not more than 150gram·force (g·f), more preferably not more than 100 g·f, and furthermorepreferably not more than 50 g·f in order to perform easy release of thetransfer layer. By using such an electrophotographic light-sensitiveelement, releasability between the transfer layer and thelight-sensitive element is more effectively revealed.

The measurement of adhesive strength is conducted according to JIS Z0237-1980 8.3.1. 180 Degrees Peeling Method with the followingmodifications:

(i) As a test plate, an electrophotographic light-sensitive element onthe surface of which a transfer layer is to be provided is used.

(ii) As a test piece, a pressure resistive adhesive tape of 6 mm inwidth prepared according to JIS C2338-1984 is used.

(iii) A peeling rate is 120 mm/min using a constant rate of traversetype tensile testing machine.

Specifically, the test piece is laid its adhesive face downward on thetest plate and a roller is reciprocate one stroke at a rate ofapproximately 300 mm/min upon the test piece for pressure sticking.Within 20 to 40 minutes after the sticking with pressure, a part of thestuck portion is peeled approximately 25 mm in length and then peeledcontinuously at the rate of 120 mm/min using the constant rate oftraverse type tensile testing machine. The strength is read at aninterval of 20 mm in length of peeling, and eventually read 4 times. Thetest is conducted on three test pieces. The mean value is determinedfrom 12 measured values for three test pieces and the resulting meanvalue is converted in terms of 10 mm in width.

The measurement of adhesive strength of a receiving material can also beconducted in the same manner as described above using the receivingmaterial to be measured as the test plate.

Examples of the electrophotographic light-sensitive element, the surfaceof which has the releasability include specifically anelectrophotographic light-sensitive element using amorphous silicon andan electrophotographic light-sensitive element containing a resin toincrease releasability which contains a silicon atom and/or a fluorineatom (hereinafter referred to as a resin (P) sometimes) in a layeradjacent to the transfer layer (X) or the uppermost layer of thelight-sensitive element which is to be come into contact with thetransfer layer (X). By using such a light-sensitive element, thetransfer layer is easily and completely transferred.

The layer containing the resin containing a silicon atom and/or afluorine atom is a layer which is adjacent to the transfer layer (X) orwhich is to be come into contact with the transfer layer (X) and may ormay not be a light-sensitive layer. A light-insensitive layer (anovercoat layer) having the releasability described above may be providedon a light-sensitive layer in order to impart the releasability from thetransfer layer (X).

Further, the resin (P) is preferably a copolymer comprising at least onepolymer segment (α) containing not less than 50% by weight of a siliconatom and/or fluorine atom-containing polymer component and at least onepolymer segment (β) containing from 0 to 20% by weight of a silicon atomand/or fluorine atom-containing polymer component, the polymer segment(α) and (β) being bonded in the form of blocks in view of furtherimprovement in the releasability from the transfer layer (X).

Moreover, a light-sensitive element whose surface has the releasabilitycan also be obtained by causing a compound (S) containing at least afluorine atom and/or a silicon atom to adsorb or adhere onto the surfaceof electrophotographic light-sensitive element in the present invention.By employing the means for imparting the releasability to alight-sensitive element as described above, an electrophotographiclight-sensitive element conventionally used can be utilized withouttaking releasability of the surface of the electrophotographiclight-sensitive element into consideration.

The transfer layer (X) may have been previously provided on alight-sensitive element or may be formed each time on thelight-sensitive element according to the present invention. Theformation of transfer layer may be performed in an apparatus differentfrom an apparatus for an electrophotographic process and a transferprocess or in the apparatus for these processes on the light-sensitiveelement each time.

It is preferred that the transfer layer (X) and the transfer layer (Y)are formed on a light-sensitive element and the transfer layer (X),respectively, by any one of a hot-melt coating method, anelectrodeposition coating method and a transfer method.

According to the present invention, the steps for forming the transferlayer (X) and transfer layer (Y) are preferably conducted in anapparatus in which the electrophotographic process and the transferprocess are carried out and the transfer layers are formed each time,since the light-sensitive element can be repeatedly employed after thetransfer layers are released therefrom without throwing it away and theelectrophotographic process can be advantageously performed in sequencewith these steps in the same apparatus, thus resulting in an operationof a low running cost.

Therefore, one preferred embodiment of the present invention is a methodof forming a color image comprising performing the following steps (i)to (iv) in the same apparatus:

(i) a step of forming a peelable transfer layer (X) on anelectrophotographic light-sensitive element,

(ii) a step of forming at least one color toner image on the transferlayer (X) by an electrophotographic process,

(iii) a step of forming a second peelable transfer layer (Y) on thetoner image, and

(iv) a step of transferring the toner image together with the transferlayer (X) and (Y) onto a receiving material.

The present invention also provides a method of forming a color imagefurther comprising a step of causing the above-described compound (S) toadsorb or adhere onto the surface of electrophotographic light-sensitiveelement before the step (i) of forming the transfer layer (X) in orderto impart the releasability to the electrophotographic light-sensitiveelement in the apparatus.

In the present invention, the step (i) of forming the first transferlayer (X) on an electrophotographic light-sensitive element is performedby means of electrodeposition or adhesion of resin grains (AR) byelectrophoresis on the surface of electrophotographic light-sensitiveelement to form a film using a dispersion for electrodepositioncomprising resin grains (AR) having a glass transition point of not morethan 140° C. or a softening point of not more than 180° C. dispersed inan electrically insulating organic solvent having a dielectric constantof not more than 3.5 and at least one compound (S) which has a fluorineatom and/or a silicon atom and is soluble at least 0.01 g per 1.0 literof the organic solvent.

Since the compound (S) having a fluorine atom and/or silicon atomcontained in the dispersion for electrodeposition forming the transferlayer tends to adsorb or adhere onto the surface of light-sensitiveelement before the electrodeposition or adhesion of dispersed resingrains (AR) by electrophoresis on the surface of light-sensitiveelement, releasability has been imparted onto the surface oflight-sensitive element at the formation of transfer layer, therebyeffectively providing transferability of the transfer layer. Accordingto such a procedure, the impartation of releasability and formation oftransfer layer onto the electrophotographic light-sensitive element canbe performed at the same time and a specific technique for impartingreleasability on the surface of light-sensitive element is notnecessary.

The preparation of a uniform and thin layer can be easily performed bysupplying resin grains (AR) between the electrophotographiclight-sensitive element and an electrode placed in face of thelight-sensitive element and migrating the resin grains (AR) byelectrophoresis according to a potential gradient applied from anexternal power source to cause the grains (AR) to electrodeposite on oradhere to the electrophotographic light-sensitive element and form afilm.

In addition, the present invention provides an apparatus for forming acolor image comprising a means for forming a first peelable transferlayer on the surface of an electrophotographic light-sensitive element,a means for forming at least one color toner image on the transfer layerby an electrophotographic process, a means for forming a second peelabletransfer layer on the toner image formed on the first transfer layer anda means for transferring the toner image together with the firsttransfer layer and the second transfer layer onto a receiving material.

The present invention also provides an apparatus for forming a colorimage further comprising a means for causing the compound (S) describedabove to adsorb or adhere onto the surface of light-sensitive element.

Now, the transfer layer which can be used in the present invention willbe described in greater detail below.

The transfer layer (X) used in the present invention is not particularlylimited as far as it is light-transmittive and capable of transmitting aradiation having a wavelength which constitutes at least one part of thespectrally sensitive region of electrophotographic light-sensitiveelement. The layer may be colored. In a case wherein duplicated imagestransferred on a receiving material are color images, particularlyfull-color images, a colorless and transparent transfer layer (X) isusually employed.

On the other hand, the transfer layer (Y) is not imposed such arestriction relating to the electrophotographic process as on thetransfer layer (X) since the transfer layer (Y) is provided on the tonerimage which has been formed. Further, the transfer layer (Y) may containa white pigment or a fluorescent whitening agent in order to increasewhiteness of a color duplicate formed on a receiving material as asupport or may contain a dye or pigment suitable for making anappropriate background color, if desired, since it constitutes theundermost layer in the color duplicate transferred on the receivingmaterial.

It is preferred that the peelable transfer layers (X) and (Y) are bothmainly composed of a thermoplastic rein (A) having a glass transitionpoint of not more than 140° C. or a softening point of not more than180° C. The resin (A) has more preferably a glass transition point ofnot more than 120° C. or a softening point of not more than 160° C., andfurther more preferably a glass transition point of not more than 100°C. or a softening point of not more than 140° C.

The resins (A) can be employed individually or as a mixture of two ormore thereof in each of these layers.

It is preferred for the transfer layer mainly composed of the resin (A)according to the present invention to be peelable under transferconditions of a temperature of not more than 180° C. and/or a pressureof not more than 30 Kgf/cm², particularly a temperature of not more than160° C. and/or a pressure of not more than 20 Kgf/cm². The transfer isperformed without arising practical problems under the above-describedconditions because it is almost unnecessary to render a device fortransfer large-sized in order to maintain the desired heat capacity andpressure for releasing and transferring the transfer layer from thesurface of light-sensitive element and the transfer is sufficientlyeffected at an appropriate transfer speed. While there is no particularlower limit thereof, it is ordinarily preferred to use a resin layerwhich is peelable under transfer condition of a temperature of not lessthan room temperature or a pressure of not less than 100 gf/cm².

The resin (A) which can be used in the present invention may be anyresins which satisfy the above described requirement on thermalproperty, and include thermoplastic resins and resins conventionallyknown as adhesive or stick. Suitable examples of such resins includeolefin polymers or copolymers, vinyl chloride copolymers, vinylidenechloride copolymers, vinyl alkanoate polymers or copolymers, allylalkanoate polymers or copolymers, polymers or copolymers of styrene orderivatives thereof, olefin-styrene copolymers, olefin-unsaturatedcarboxylic ester copolymers, acrylonitrile copolymers, methacrylonitrilecopolymers, alkyl vinyl ether copolymers, acrylic ester polymers orcopolymers, methacrylic ester polymers or copolymers, styrene-acrylicester copolymers, styrene-methacrylic ester copolymers, itaconic diesterpolymers or copolymers, maleic anhydride copolymers, acrylamidecopolymers, methacrylamide copolymers, hydroxy-modified silicone resins,polycarbonate resins, ketone resins, polyester resins, silicone resins,amide resins, hydroxy- or carboxy-modified polyester resins, butyralresins, polyvinyl acetal resins, cyclized rubber-methacrylic estercopolymers, cyclized rubber-acrylic ester copolymers, copolymerscontaining a heterocyclic ring (the heterocyclic ring including, forexample, furan, tetrahydrofuran, thiophene, dioxane, dioxofuran,lactone, benzofuran, benzothiophene and 1,3-dioxetane rings), celluloseresins, fatty acid-modified cellulose resins and epoxy resins. Specificexamples of resins are described, e.g., in Plastic Zairyo Koza Series,Vols. 1 to 18, Nikkan Kogyo Shinbunsha (1981), Kinki Kagaku Kyokai VinylBukai (ed.), Polyenka Vinyl, Nikkan Kogyo Shinbunsha (1988), Eizo Omori,Kinosei Acryl Jushi, Techno System (1985), Ei-ichiro Takiyama, PolyesterJushi Handbook, Nikkan Kogyo Shinbunsha (1988), Kazuo Yuki, HowaPolyester Jushi Handbook, Nikkan Kogyo Shinbunsha (1989), KobunshiGakkai (ed.), Kobunshi Data Handbook (Oyo-hen), Ch. 1, Baifukan (1986),Yuji Harasaki, Saishin Binder Gijutsu Binran, Ch. 2, Sogo Gijutsu Center(1985), Taira Okuda (ed.), Kobunshi Kako, Vol. 20, Supplement"Nenchaku", Kobunshi Kankokai (1976), Keizi Fukazawa, Nenchaku Gijutsu,Kobunshi Kankokai (1987), Mamoru Nishiguchi, Secchaku Binran, 14th Ed.,Kobunshi Kankokai (1985), and Nippon Secchaku Kokai (ed.), SecchakuHandbook, 2nd Ed., Nikkan Kogyo Shinbunsha (1980).

In a preferred embodiment, the transfer layer (X) is mainly composed ofa thermoplastic resin (AH) having a glass transition point of from 10°C. to 140° C. or a softening point of from 35° C. to 180° C., morepreferably a glass transition point of from 15° C. to 120° C. or asoftening point of from 40° C. to 140° C.

The transfer layer (Y) is mainly composed of a thermoplastic resin (AL)having a glass transition point of not less than 45° C. or a softeningpoint of not less than 60° C., more preferably a glass transition pointof from -40° C. to 40° C. or a softening point of from -20° C. to 60°C., and a difference in the glass transition point or softening pointbetween the resin (AH) used in transfer layer (X) and the resin (AL)used in transfer layer (Y) is at least 2° C. More preferably, a glasstransition point or softening point of resin (AL) is at least 5° C.lower than one of resin (AH). The difference in the glass transitionpoint or softening point between the resin (AH) and the resin (AL) meansa difference between the lowest glass transition point or softeningpoint of those of the resins (AH) and the highest glass transition pointor softening point of those of the resins (AL) when two or more of theresins (AH) and/or resins (AL) are employed.

A weight average molecular weight of the resin (AH) is preferably from1×10³ to 1×10⁶, more preferably from 3×10³ to 5×10⁵. Also, a weightaverage molecular weight of the resin (AL) is preferably from 3×10³ to1×10⁶, more preferably from 5×10³ to 5×10⁵.

According to the present invention, the resin (AH) and resin (AL) eachhaving a glass transition point or a softening point in theabove-described range are appropriately selected from the resins (A)descrbed above.

The thermoplastic resins (AH) and/or (AL) used in the transfer layer ofthe present invention preferably contains a polymer component (F)containing a moiety having a fluorine atom and/or a silicon atom whichhas an effect to increase the releasability of the resin (A) itself as apolymer component in the resin described above.

The moiety having a fluorine atom and/or a silicon atom may beincorporated into the main chain of the polymer or contained as asubstituent in the side chain of the polymer.

The polymer components (F) are preferably present as a block in theresin (A). The content of polymer component (F) is preferably from 3 to40% by weight, more preferably from 5 to 25% by weight of the totalpolymer components of the resin (A) (including the resins (AH) and(AL)). The polymer component (F) containing a fluorine atom and/or asilicon atom may be incorporated into any of the resin (AH) and resin(AL). It is desirable to incorporate the polymer component (F) into theresin (AH) in order to effectively increase the releasability of thetransfer layer from the electrophotographic light-sensitive element,resulting in improvement of the transferability.

The polymer component (F) which has an effect for increasing thereleasability of the resin (A) itself will be described below.

The fluorine atom-containing moieties include monovalent or divalentorganic residues, for example, --C_(h) F_(2h+1) (wherein h represents aninteger of from 1 to 18), --(CF₂)_(j) CF₂ H (wherein j represents aninteger of from 1 to 17), --CFH₂, ##STR1## (wherein r represents aninteger of from 1 to 5), --CF₂ --, --CFH--, ##STR2## (wherein krepresents an integer of from 1 to 4).

The silicon atom-containing moieties include monovalent or divalentorganic residues, for example, ##STR3## wherein R¹¹, R¹², R¹³, R¹⁴, andR¹⁵, which may be the same or different, each represents a hydrocarbongroup which may be substituted or --OR¹⁶ wherein R¹⁶ represents ahydrocarbon group which may be substituted.

The hydrocarbon group represented by R¹¹, R¹², R¹³, R¹⁴, R¹⁵ or R¹⁶include specifically an alkyl group having from 1 to 18 carbon atomswhich may be substituted (e.g., methyl, ethyl, propyl, butyl, hexyl,octyl, decyl, dodecyl, hexadecyl, 2-chloroethyl, 2-bromoethyl,2,2,2-trifluoroethyl, 2-cyanoethyl, 3,3,3-trifluoropropyl,2-methoxyethyl, 3-bromopropyl, 2-methoxycarbonylethyl, or2,2,2,2',2',2'-hexafluoroisopropyl), an alkenyl group having from 4 to18 carbon atoms which may be substituted (e.g., 2-methyl-1-propenyl,2-butenyl, 2-pentenyl, 3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl,2-hexenyl, or 4-methyl-2-hexenyl), an aralkyl group having from 7 to 12carbon atoms which may be substituted (e.g., benzyl, phenethyl,3-phenylpropyl, naphthylmethyl, 2-naphthylethyl, chlorobenzyl,bromobenzyl, methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl,or dimethoxybenzyl), an alicyclic group having from 5 to 8 carbon atomswhich may be substituted (e.g., cyclohexyl, 2-cyclohexylethyl, or2-cyclopentylethyl), or an aromatic group having from 6 to 12 carbonatoms which may be substituted (e.g., phenyl, naphthyl, tolyl, xylyl,propylphenyl, butylphenyl, octylphenyl, dodecylphenyl, methoxyphenyl,ethoxyphenyl, butoxyphenyl, decyloxyphenyl, chlorophenyl,dichlorophenyl, bromophenyl, cyanophenyl, acetylphenyl,methoxycarbonylphenyl, ethoxycarbonylphenyl, butoxycarbonylphenyl,acetamidophenyl, propionamidophenyl, or dodecyloylamidophenyl).

The fluorine atom and/or silicon atom-containing organic residue may becomposed of a combination thereof. In such a case, they may be combinedeither directly or via a linking group. The linking groups includedivalent organic residues, for example, divalent aliphatic groups,divalent aromatic groups, and combinations thereof, which may or may notcontain a bonding group, e.g., ##STR4## wherein d¹ has the same meaningas R¹¹ above.

Examples of the divalent aliphatic groups are shown below. ##STR5##wherein e¹ and e², which may be the same or different, each represents ahydrogen atom, a halogen atom (e.g., chlorine or bromine) or an alkylgroup having from 1 to 12 carbon atoms (e.g., methyl, ethyl, propyl,chloromethyl, bromomethyl, butyl, hexyl, octyl, nonyl or decyl); and Qrepresents ##STR6## wherein d² represents an alkyl group having from 1to 4 carbon atoms, --CH₂ Cl, or --CH₂ Br.

Examples of the divalent aromatic groups include a benzene ring, anaphthalene ring, and a 5- or 6-membered heterocyclic ring having atleast one hetero atom selected from an oxygen atom, a sulfur atom and anitrogen atom. The aromatic groups may have a substituent, for example,a halogen atom (e.g., fluorine, chlorine or bromine), an alkyl grouphaving from 1 to 8 carbon atoms (e.g., methyl, ethyl, propyl, butyl,hexyl or octyl) or an alkoxy group having from 1 to 6 carbon atoms(e.g., methoxy, ethoxy, propoxy or butoxy). Examples of the heterocyclicring include a furan ring, a thiophene ring, a pyridine ring, apiperazine ring, a tetrahydrofuran ring, a pyrrole ring, atetrahydropyran ring, and a 1,3-oxazoline ring.

Specific examples of the repeating units having the fluorine atom and/orsilicon atom-containing moiety as described above are set forth below,but the present invention should not be construed as being limitedthereto. In formulae (F-1) to (F-32) below, R_(f) represents any one ofthe following groups of from (1) to (11); and b represents a hydrogenatom or a methyl group. ##STR7## wherein Rf' represents any one of theabove-described groups of from (1) to (8); n represents an integer offrom 1 to 18; m represents an integer of from 1 to 18; and p representsan integer of from 1 to 5. ##STR8##

A preferred embodiment of the block copolymer in the resin (A)according. to the present invention will be described below. Any type ofcopolymer can be used as far as the fluorine atom and/or siliconatom-containing polymer components are contained as a block in theresins (A). The term "to be contained as a block" means that the resinhas a polymer segment comprising at least 70 by weight of the fluorineatom and/or silicon atom-containing polymer component based on thepolymer segment. The forms of blocks include an A-B type block, an A-B-Atype block, a B-A-B type block, a graft type block, and a starlike typeblock as schematically illustrated below. ##STR9##

These various types of block copolymers can be synthesized in accordancewith conventionally known polymerization methods. Useful methods aredescribed, e.g., in W. J. Burlant and A. S. Hoffman, Block and GraftPolymers, Reuhold (1986), R. J. Cevesa, Block and Graft Copolymers,Butterworths (1962), D. C. Allport and W. H. James, Block Copolymers,Applied Sci. (1972), A. Noshay and J. E. McGrath, Block Copolymers,Academic Press (1977), G. Huvtreg, D. J. Wilson, and G. Riess, NATOASIser. SerE., Vol. 1985, p. 149, and V. Perces, Applied Polymer Sci.,Vol. 285, p. 95 (1985).

For example, ion polymerization reactions using an organometalliccompound (e.g., an alkyl lithium, lithium diisopropylamide, an alkalimetal alcoholate, an alkylmagnesium halide, or an alkylaluminum halide)as a polymerization initiator are described, for example, in T. E.Hogeu-Esch and J. Smid, Recent Advances in Anion Polymerization,Elsevier (New York) (1987), Yoshio Okamoto, Kobunshi, Vol. 38, p. 912(1989), Mitsuo Sawamoto, Kobunshi, Vol. 38, p. 1018 (1989), TadashiNarita, Kobunshi, Vol. 37, p. 252 (1988), B. C. Anderson, et al.,Macromolecules, Vol. 14, p. 1601 (1981), and S. Aoshima and T.Higasimura, Macromolecules, Vol. 22, p. 1009 (1989).

Ion polymerization reactions using a hydrogen iodide/iodine system aredescribed, for example, in T. Higashimura, et al., Macromol. Chem.,Macromol. Symp., Vol. 13/14, p. 457 (1988), and Toshinobu Higashimuraand Mitsuo Sawamoto, Kobunshi Ronbunshu, Vol. 46, p. 189 (1989).

Group transfer polymerization reactions are described, for example, inD. Y. Sogah, et al., Macromolecules, Vol. 22, p. 1473 (1987), O. W.Webster and D. Y. Sogah, Kobunshi, Vol. 36, p. 808 (1987), M. T. Reetg,et al., Angew. Chem. Int. Ed. Engl., Vol. 25, p. 9108 (1986), andJP-A-63-97609.

Living polymerization reactions using a metalloporphyrin complex aredescribed, for example, in T. Yasuda, T. Aida, and S. Inoue,Macromolecules, Vol. 17, p. 2217 (1984), M. Kuroki, T. Aida, and S.Inoue, J. Am. Chem. Soc., Vol. 109, p. 4737 (1987), M. Kuroki, et al.,Macromolecules, Vol. 21, p. 3115 (1988), and M. Kuroki and I. Inoue,Yuki Gosei Kagaku, Vol. 47, p. 1017 (1989).

Ring-opening polymerization reactions of cyclic compounds are described,for example, in S. Kobayashi and T. Saegusa, Ring OpeningPolymerization, Applied Science Publishers Ltd. (1984), W. Seeliger, etal., Angew. Chem. Int. Ed. Engl., Vol. 5, p. 875 (1966), S. Kobayashi,et al., Poly. Bull., Vol. 13, p. 447 (1985), and Y. Chujo, et al.,Macromolecules, Vol. 22, p. 1074 (1989).

Photo living polymerization reactions using a dithiocarbamate compoundor a xanthate compound, as an initiator are described, for example, inTakayuki Otsu, Kobunshi, Vol. 37, p. 248 (1988), Shun-ichi Himori andKoichi Otsu, Polymer Rep. Jap., Vol. 37, p. 3508 (1988), JP-A-64-111,JP-A-64-26619, and M. Niwa, Macromolecules, Vol. 189, p. 2187 (1988).

Radical polymerization reactions using a polymer containing an azo groupor a peroxide group as an initiator to synthesize block copolymers aredescribed, for example, in Akira Ueda, et al., Kobunshi Ronbunshu, Vol.33, p. 931 (1976), Akira Ueda, Osaka Shiritsu Kogyo Kenkyusho Hokoku,Vol. 84 (1989), O. Nuyken, et al., Macromol. Chem., Rapid. Commun., Vol.9, p. 671 (1988), and Ryohei Oda, Kagaku to Kogyo, Vol. 61, p. 43(1987).

Syntheses of graft type block copolymers are described in theabove-cited literature references and, in addition, Fumio Ide, GraftJugo to Soho Oyo, Kobunshi Kankokai (1977), and Kobunshi Gakkai (ed.),Polymer Alloy, Tokyo Kagaku Dojin (1981). For example, known graftingtechniques including a method of grafting of a polymer chain by apolymerization initiator, an actinic ray (e.g., radiant ray, electronbeam), or a mechano-chemical reaction; a method of grafting withchemical bonding between functional groups of polymer chains (reactionbetween polymers); and a method of grafting comprising a polymerizationreaction of a macromonomer may be employed.

The methods of grafting using a polymer are described, for example, inT. Shiota, et al., J. Appl. Polym. Sci., Vol. 13, p. 2447 (1969), W. H.Buck, Rubber Chemistry and Technology, Vol. 50, p. 109 (1976), TsuyoshiEndo and Tsutomu Uezawa, Nippon Secchaku Kyokaishi, Vol. 24, p. 323(1988), and Tsuyoshi Endo, ibid., Vol. 25, p. 409 (1989).

The methods of grafting using a macromonomer are described, for example,in P. Dreyfuss and R. P. Quirk, Encycl. Polym. Sci. Eng., Vol. 7, p. 551(1987), P. F. Rempp and E. Franta, Adv. Polym. Sci., Vol. 58, p. 1(1984), V. Percec, Appl. Poly. Sci., Vol. 285, p. 95 (1984), R. Asamiand M. Takari, Macromol. Chem. Suppl., Vol. 12, p. 163 (1985), P. Rempp,et al., Macromol. Chem. Suppl., Vol. 8, p. 3 (1985), Katsusuke Kawakami,Kagaku Kogyo, Vol. 38, p. 56 (1987), Yuya Yamashita, Kobunshi, Vol. 31,p. 988 (1982), Shiro Kobayashi, Kobunshi, Vol. 30, p. 625 (1981),Toshinobu Higashimura, Nippon Secchaku Kyokaishi, Vol. 18, p. 536(1982), Koichi Itoh, Kobunshi Kako, Vol. 35, p. 262 (1986), TakashiroAzuma and Takashi Tsuda, Kino Zairyo, Vol. 1987, No. 10, p. 5, YuyaYamashita (ed.), Macromonomer no Kagaku to Kogyo, I.P.C. (1989),Tsuyoshi Endo (ed.), Atarashii Kinosei Kobunshi no Bunshi Sekkei, Ch. 4,C.M.C. (1991), and Y. Yamashita, et al., Polym. Bull., Vol. 5, p. 361(1981).

Syntheses of starlike block copolymers are described, for example, in M.T. Reetz, Angew. Chem. Int. Ed. Engl., Vol. 27, p. 1373 (1988), M.Sgwarc, Carbanions, Living Polymers and Electron Transfer Processes,Wiley (New York) (1968), B. Gordon, et al., Polym. Bull., Vol. 11, p.349 (1984), R. B. Bates, et al., J. Org. Chem., Vol. 44, p. 3800 (1979),Y. Sogah, A.C.S. Polym. Rapr., Vol. 1988, No. 2, p. 3, J. W. Mays,Polym. Bull., Vol. 23, p. 247 (1990), I. M. Khan et al., Macromolecules,Vol. 21, p. 2684 (1988), A. Morikawa, Macromolecules, Vol. 24, p. 3469(1991), Akira Ueda and Toru Nagai, Kobunshi, Vol. 39, p. 202 (1990), andT. Otsu, Polymer Bull., Vol. 11, p. 135 (1984).

While reference can be made to known techniques described in theliteratures cited above, the method for synthesizing the blockcopolymers according to the present invention is not limited to thesemethods.

The resin (A) is preferably used at least 70% by weight, more preferablyat least 90% by weight based on the total amount of the composition forthe transfer layer. The resin (A) may be used individually or as amixture of two or more thereof.

If desired, the transfer layer (X) or (Y) may contain various additivesfor improving physical characteristics, such as adhesion, film-formingproperty, and film strength. For example, rosin, petroleum resin, orsilicone oil may be added for controlling adhesion; polybutene, DOP,DBP, low-molecular weight styrene resins, low molecular weightpolyethylene wax, microcrystalline wax, or paraffin wax, as aplasticizer or a softening agent for improving wetting property to thelight-sensitive element or decreasing melting viscosity; and a polymerichindered polyvalent phenol, or a triazine derivative, as an antioxidant.For the details, reference can be made to Hiroshi Fukada, Hot-meltSecchaku no Jissai, pp. 29 to 107, Kobunshi Kankokai (1983).

Each thickness of the transfer layer (X) and transfer layer (Y) ispreferably in a range of from 0.1 to 10 μm, more preferably in a rangeof from 0.5 to 7 μm. If the thickness of each of the transfer layer (X)and transfer layer (Y) is 0.1 μm or more, the sufficient effect of thesetransfer layers is obtained.

Now, an electrophotographic light-sensitive element having thereleasability on which the transfer layer is formed will be described indetail below.

Any conventionally known electrophotographic light-sensitive element canbe employed. What is important is that the surface of thelight-sensitive element has the releasability at the time for theformation of transfer layer so as to easily release the transfer layerprovided thereon together with toner images. Specifically, in thepresent invention, an adhesive strength of the surface oflight-sensitive element measured according to JIS Z 0237-1980 "TestingMethods of pressure sensitive adhesive tapes and sheets" is preferablynot more than 150 g·f, more preferably not more than 100 g·f, andparticularly preferably not more than 50 g·f, at the time for theformation of transfer layer (X) or before the formation of toner image.While an electrophotographic light-sensitive element which has alreadythe surface exhibiting the desired releasability can be employed in thepresent invention, it is also possible to cause a compound (S)containing at least a fluorine atom and/or a silicon atom to adsorb oradhere onto the surface of electrophotographic light-sensitive elementfor imparting the releasability thereto before the formation of transferlayer (X). Thus, conventional electrophotographic light-sensitiveelements can be utilized without taking releasability of the surfacethereof into consideration.

Further, when releasability of the surface of electrophotographiclight-sensitive element tends to decrease during repeated use of thelight-sensitive element having the surface releasability according tothe present invention the method for adsorbing or adhering a compound(S) can be applied. By the method, the releasability of light-sensitiveelement is easily maintained.

The impartation of releasability onto the surface of electrophotographiclight-sensitive element is preferably carried out in an apparatus forforming a color image, and specifically a means for causing the compound(S) to adsorb or adhere onto the surface of electrophotographiclight-sensitive element is further provided in the apparatus for forminga color image.

In order to obtain a light-sensitive element having a surface of thereleasability, there are a method of selecting a light-sensitive elementpreviously having such a surface of the releasability, a method ofimparting the releasability to a surface of electrophotographiclight-sensitive element conventionally employed by causing the compound(S) for imparting releasability to adsorb or adhere onto the surface oflight-sensitive element, and a method of forming a transfer layer on alight-sensitive element by an electrodeposition coating method using adispersion for electrodeposition containing the compound (S) forimparting releasability to simultaneously conduct the impartation ofreleasability and formation of transfer layer on the light-sensitiveelement.

Suitable examples of the light-sensitive elements previously having thesurface of releasability used in the first method include thoseemploying a photoconductive substance which is obtained by modifying asurface of amorphous silicon to exhibit the releasability.

For the purpose of modifying the surface of electrophotographiclight-sensitive element mainly containing amorphous silicon to have thereleasability, there is a method of treating a surface of amorphoussilicon with a coupling agent containing a fluorine atom and/or asilicon atom (for example, a silane coupling agent or a titaniumcoupling agent) as described, for example, in JP-A-55-89844,JP-A-4-231318, JP-A-60-170860, JP-A-59-102244 and JP-A-60-17750. Also, amethod of adsorbing and fixing the compound (S) according to the presentinvention, particularly a releasing agent containing a component havinga fluorine atom and/or a silicon atom as a substituent in the form of ablock (for example, a polyether-modified polydialkylsilicone or acarboxylic acid-, amino group- or carbinol-modified polydialkylsilicone)as described in detail below can be employed.

Further, another example of the light-sensitive elements previouslyhaving the surface of releasability is an electrophotographiclight-sensitive element containing a polymer having a polymer componentcontaining a fluorine atom and/or a silicon atom in a region near to thesurface thereof.

The term "region near to the surface of electrophotographiclight-sensitive element" used herein means the uppermost layer of thelight-sensitive element and includes an overcoat layer provided on aphotoconductive layer and the uppermost photoconductive layer.Specifically, an overcoat layer is provided on the light-sensitiveelement having a photosensitive layer as the uppermost layer whichcontains the above-described polymer to impart the releasability, or theabove-described polymer is incorporated into the uppermost layer of aphotoconductive layer (including a single photoconductive layer and alaminated photoconductive layer) to modify the surface thereof so as toexhibit the releasability. By using such a light-sensitive element, thetransfer layer can be easily and completely transferred since thesurface of the light-sensitive element has the good releasability.

In order to impart the releasability to the overcoat layer or theuppermost photoconductive layer, a polymer containing a silicon atomand/or a fluorine atom is used as a binder resin of the layer. It ispreferred to use a small amount of a block copolymer containing apolymer segment comprising a silicon atom and/or fluorineatom-containing polymer component described in detail below (hereinafterreferred to as a surface-localized type copolymer sometimes) incombination with other binder resins. Further, such polymers containinga silicon atom and/or a fluorine atom are employed in the form ofgrains.

In the case of providing an overcoat layer, it is preferred to use theabove-described surface-localized type block copolymer together withother binder resins of the layer for maintaining sufficient adhesionbetween the overcoat layer and the photoconductive layer. Thesurface-localized type copolymer is ordinarily used together with otherbinder resins in a proportion of from 0.1 to 20 parts by weight per 100parts by weight of the total composition of the overcoat layer.

Specific examples of the overcoat layer include a protective layer whichis a surface layer provided on the light-sensitive element forprotection known as one means for ensuring durability of the surface ofa light-sensitive element for a plain paper copier (PPC) using a drytoner against repeated use.

For instance, techniques relating to a protective layer using a silicontype block copolymer are described, for example, in JP-A-61-95358,JP-A-55-83049, JP-A-62-87971, JP-A-61-189559, JP-A-62-75461,JP-A-61-139556, JP-A-62-139557, and JP-A-62-208055. Techniques relatingto a protective layer using a fluorine type block copolymer aredescribed, for example, in JP-A-61-116362, JP-A-61-117563,JP-A-61-270768, and JP-A-62-14657. Techniques relating to a protectinglayer using grains of a resin containing a fluorine-containing polymercomponent in combination with a binder resin are described inJP-A-63-249152 and JP-A-63-221355.

On the other hand, the method of modifying the surface of the uppermostphotoconductive layer so as to exhibit the releasability is effectivelyapplied to a so-called disperse type light-sensitive element whichcontains at least a photoconductive substance and a binder resin.

Specifically, a layer constituting the uppermost layer of aphotoconductive layer is made to contain either one or both of a blockcopolymer resin comprising a polymer segment containing a fluorine atomand/or silicon atom-containing polymer component as a block and resingrains containing a fluorine atom and/or silicon atom-containing polymercomponent, whereby the resin material migrates to the surface of thelayer and is concentrated and localized there to have the surfaceimparted with the releasability. The copolymers and resin grains whichcan be used include those described in JP-A-5-197169.

In order to further ensure surface localization, a block copolymercomprising at least one fluorine atom and/or fluorine atom-containingpolymer segment and at least one polymer segment containing a photo-and/or heat-curable group-containing component as blocks can be used asa binder resin for the overcoat layer or the photoconductive layer.Examples of such polymer segments containing a photo- and/orheat-curable group-containing component are described in JP-A-5-197169.Alternatively, a photo- and/or heat-curable resin may be used incombination with the fluorine atom and/or silicon atom-containing resinin the present invention.

The polymer comprising a polymer component containing a fluorine atomand/or a silicon atom effectively used for modifying the surface of theelectrophotographic light-sensitive element in the manner as describedabove to obtain the electrophotographic light-sensitive element havingthe surface of releasability as well as the electrophotographiclight-sensitive element mainly containing amorphous silicon may be inthe form of a resin (hereinafter referred to as a resin (P) sometimes)or a resin grain (hereinafter referred to as a resin grain (L)sometimes).

Where the polymer containing a fluorine atom and/or siliconatom-containing polymer component used in the present invention is arandom copolymer, the content of the fluorine atom and/or siliconatom-containing polymer component is preferably at least 60% by weight,and more preferably at least 80% by weight based on the total polymercomponent.

In a preferred embodiment, the above-described polymer is a blockcopolymer comprising at least one polymer segment (α) containing atleast 50% by weight of a fluorine atom and/or silicon atom-containingpolymer component and at least one polymer segment (β) containing 0 to20% by weight of a fluorine atom and/or silicon atom-containing polymercomponent, the polymer segments (α) and (β) being bonded in the form ofblocks. More preferably, the polymer segment (β) of the block copolymercontains at least one polymer component containing at least one photo-and/or heat-curable functional group.

It is preferred that the polymer segment (β) of the block copolymer doesnot contain any fluorine atom and/or silicon atom-containing polymercomponent.

As compared with the random copolymer, the block copolymer comprisingthe polymer segments (α) and (β) (surface-localized type copolymer) ismore effective not only for improving the surface releasability but alsofor maintaining such a releasability.

More specifically, where a film is formed in the presence of a smallamount of resin (P) and/or resin grains (L) containing a fluorine atomand/or a silicon atom, the resins (P) or resin grains (L) easily migrateto the surface portion of the film and are concentrated there by the endof a drying step of the film to thereby modify the film surface so as toexhibit the releasability.

Where the resin (P) is the block copolymer in which the fluorine atomand/or silicon atom-containing polymer segment exists as a block, theother polymer segment containing no, or if any a small proportion of,fluorine atom and/or silicon atom-containing polymer componentundertakes sufficient interaction with the film-forming binder resinsince it has good compatibility therewith. Thus, during the formation ofthe transfer layer on the light-sensitive element, further migration ofthe resin into the transfer layer is inhibited or prevented by an anchoreffect to form and maintain the definite interface between the transferlayer and the light-sensitive element.

Further, where the segment (β) of the block copolymer contains a photo-and/or heat-curable group, crosslinking between the polymer moleculestakes place during the film formation to thereby ensure retention of thereleasability at the interface between the light-sensitive element andthe transfer layer.

The above-described polymer may be used in the form of resin grains asdescribed above. Preferred resin grains (L) are resin grains dispersiblein a non-aqueous solvent. Such resin grains are composed of a blockcopolymer comprising a non-aqueous solvent-insoluble polymer segmentwhich contains a fluorine atom and/or silicon atom-containing polymercomponent and a non-aqueous solvent-soluble polymer segment whichcontains no, or if any not more than 20% of, fluorine atom and/orsilicon atom-containing polymer component.

Where the resin grains (L) are used in combination with a binder resin,the insolubilized polymer segment undertakes migration and concentrationof the grains to the surface portion while the soluble polymer segmentexerts an interaction with the binder resin (an anchor effect) similarlyto the above-described resin. When the resin grains contain a photo-and/or heat-curable group, further migration of the grains to thetransfer layer can be avoided.

The polymer component containing a moiety having a fluorine atom and/ora silicon atom used in the resin (P) and resin grain (L) is the same asthe polymer component (F) which may be incorporated into the resin (A)employed in the transfer layer described hereinbefore.

In the so-called surface-localized type copolymers of the resins (P) andresin grains (L), the content of the silicon atom and/or fluorineatom-containing polymer component present in the segment (α) is at least50% by weight, preferably at least 70% by weight, and more preferably atleast 80% by weight.

Also, the content of the fluorine atom and/or silicon atom-containingpolymer component in the segment (β) is not more than 20% by weight, andpreferably 0% by weight.

A weight ratio of segment (α)/segment (β) ranges usually from 1/99 to95/5, and preferably from 5/95 to 90/10. In the range described above,the good migration effect and anchor effect of the resin (P) or resingrain (L) at the surface region of light-sensitive element are obtained.

The resin (P) preferably has a weight average molecular weight of from5×10³ to 1×10⁶, and more preferably from 1×10⁴ to 5×10⁵. The segment (α)in the resin (P) preferably has a weight average molecular weight of atleast 1×10³.

The resin grain (L) preferably has an average grain diameter of from0.001 to 1 μm, and more preferably from 0.05 to 0.5 μm.

A preferred embodiment of the so-called surface-localized type copolymerin the resin (P) will be described below.

Any type of the block copolymer can be used as far as the fluorine atomand/or silicon atom-containing polymer components are contained thereinas a block. The term "to be contained as a block" means that the polymerhas the polymer segment containing at least 50% by weight of thefluorine atom and/or silicon atom-containing polymer component based onthe weight of the polymer segment. The forms of blocks include, forexample, an A-B type block, an A-B-A type block, a B-A-B type block, agraft type block, and a starlike type block as described with respect tothe resin (A) used in the transfer layer above.

These various types of block copolymers of the resins (P) can besynthesized in accordance with conventionally known polymerizationmethods. Specifically, methods described for the resin (A) containingthe polymer components (F) as a block can be employed.

A preferred embodiment of the resin grains (L) according to the presentinvention will be described below.

As described above, the resin grains (L) preferably comprise thefluorine atom and/or silicon atom-containing polymer segment (α)insoluble in a non-aqueous solvent and the polymer segment (β) which issoluble in a non-aqueous solvent and contains substantially no fluorineatom and/or silicon atom. The polymer segment (α) constituting theinsoluble portion of the resin grain may have a crosslinked structure.

Preferred methods for synthesizing the resin grains (L) include thenon-aqueous dispersion polymerization method hereinbefore described withrespect to the non-aqueous solvent-dispersed resin grains.

The non-aqueous solvents which can be used in the preparation of thenon-aqueous solvent-dispersed resin grains include any organic solventshaving a boiling point of not more than 200° C., either individually orin combination of two or more thereof.

Specific examples of the organic solvent include alcohols such asmethanol, ethanol, propanol, butanol, fluorinated alcohols and benzylalcohol, ketones such as acetone, methyl ethyl ketone, cyclohexanone anddiethyl ketone, ethers such as diethyl ether, tetrahydrofuran anddioxane, carboxylic acid esters such as methyl acetate, ethyl acetate,butyl acetate and methyl propionate, aliphatic hydrocarbons containingfrom 6 to 14 carbon atoms such as hexane, octane, decane, dodecane,tridecane, cyclohexane and cyclooctane, aromatic hydrocarbons such asbenzene, toluene, xylene and chlorobenzene, and halogenated hydrocarbonssuch as methylene chloride, dichloroethane, tetrachloroethane,chloroform, methylchloroform, dichloropropane and trichloroethane.However, the present invention should not be construed as being limitedthereto.

Dispersion polymerization in such a non-aqueous solvent system easilyresults in the production of mono-dispersed resin grains having anaverage grain diameter of not greater than 1 μm with a very narrow sizedistribution.

More specifically, a monomer corresponding to the polymer componentconstituting the segment (α) (hereinafter referred to as a monomer (a))and a monomer corresponding to the polymer component constituting thesegment (β) (hereinafter referred to as a monomer (b)) are polymerizedby heating in a non-aqueous solvent capable of dissolving a monomer (a)but incapable of dissolving the resulting polymer in the presence of apolymerization initiator, for example, a peroxide (e.g., benzoylperoxide or lauroyl peroxide), an azobis compound (e.g.,azobisisobutyronitrile or azobisisovaleronitrile), or an organometalliccompound (e.g., butyl lithium). Alternatively, a monomer (a) and apolymer comprising the segment (β) (hereinafter referred to as a polymer(Pβ)) are polymerized in the same manner as described above.

Further, the inside of the resin grain (L) may have a crosslinkedstructure. The formation of crosslinked structure can be conducted byany of conventionally known techniques.

For example, (1) a method wherein a polymer containing the polymersegment (α) is crosslinked in the presence of a crosslinking agent or acuring agent; (2) a method wherein at least the monomer (a)corresponding to the polymer segment (α) is polymerized in the presenceof a polyfunctional monomer or oligomer containing at least twopolymerizable functional groups to form a network structure overmolecules; or (3) a method wherein the polymer segment (α) and a polymercontaining a reactive group-containing polymer component are subjectedto a polymerization reaction or a polymer reaction to cause crosslinkingmay be employed.

The crosslinking agents to be used in the method (1) include compoundscommonly employed as crosslinking agents as described, e.g., in ShinzoYamashita and Tosuke Kaneko (ed.), Kakyozai Handbook, Taiseisha (1981)and Kobunshi Gakkai (ed.), Kobunshi Data Handbook (Kisohen), Baifukan(1986).

Specific examples of suitable crosslinking agents include organosilanecompounds (such as those known as silane Coupling agents, e.g.,vinyltrimethoxysilane, vinyltributoxysilane,γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, andγ-aminopropyltriethoxysilane), polyisocyanate compounds (e.g., toluylenediisocyanate, diphenylmethane diisocyanate, triphenylmethanetriisocyanate, polymethylenepolyphenyl isocyanate, hexamethylenediisocyanate, isophorone diisocyanate, and polymeric polyisocyanates),polyol compounds (e.g., 1,4-butanediol, polyoxypropylene glycol,polyoxyethylene glycols, and 1,1,1-trimethylolpropane), polyaminecompounds (e.g., ethylenediamine, γ-hydroxypropylated ethylenediamine,phenylenediamine, hexamethylenediamine, N-aminoethylpiperazine, andmodified aliphatic polyamines), polyepoxy-containing compounds and epoxyresins (e.g., the compounds as described in Hiroshi Kakiuchi (ed.),Shin-Epoxy Jushi, Shokodo (1985) and Kuniyuki Hashimoto (ed.), EpoxyJushi, Nikkan Kogyo Shinbunsha (1969)), melamine resins (e.g., thecompounds as described in Ichiro Miwa and Hideo Matsunaga (ed.),Urea.Melamine Jushi, Nikkan Kogyo Shinbunsha (1969)), andpoly(meth)acrylate compounds (e.g., the compounds as described in ShinOkawara, Takeo Saegusa, and Toshinobu Higashimura (ed.), Oligomer,Kodansha (1976), and Eizo Omori, Kinosei Acryl-kei Jushi, Techno System(1985)).

Specific examples of the polymerizable functional groups which arecontained in the polyfunctional monomer or oligomer (the monomer willsometimes be referred to as a polyfunctional monomer (d)) having two ormore polymerizable functional groups used in the method (2) aboveinclude CH₂ ═CH--CH₂ --, CH₂ ═CH--CO--O--, CH₂ ═CH--, CH₂═C(CH₃)--CO--O--, CH(CH₃)═CH--CO--O--, CH₂ ═CH--CONH--, CH₂═C(CH₃)--CONH--, CH(CH₃)═CH--CONH--, CH₂ ═CH--O--CO--, CH₂═C(CH₃)--O--CO--, CH₂ ═CH--CH₂ --O--CO--, CH₂ ═CH--NHCO--, CH₂ ═CHCH₂--NHCO--, CH₂ ═CH--SO₂ --, CH₂ ═CH--CO--, CH₂ ═CH--O--, and CH₂═CH--S--. The two or more polymerizable functional groups present in thepolyfunctional monomer or oligomer may be the same or different.

Specific examples of the monomer or oligomer having the same two or morepolymerizable functional groups include styrene derivatives (e.g.,divinylbenzene and trivinylbenzene); methacrylic, acrylic or crotonicacid esters, vinyl ethers or allyl ethers of polyhydric alcohols (e.g.,ethylene glycol, diethylene glycol, triethylene glycol, polyethyleneglycol 200, 400 or 600, 1,3-butylene glycol, neopentyl glycol,dipropylene glycol, polypropylene glycol, trimethylolpropane,trimethylolethane, and pentaerythritol) or polyhydric phenols (e.g.,hydroquinone, resorcin, catechol, and derivatives thereof); vinylesters, allyl esters, vinyl amides, or allyl amides of dibasic acids(e.g., malonic acid, succinic acid, glutaric acid, adipic acid, pimelicacid, maleic acid, phthalic acid, and itaconic acid); and condensationproducts of polyamines (e.g., ethylenediamine, 1,3-propylenediamine, and1,4-butylenediamine) and vinyl group-containing carboxylic acids (e.g.,methacrylic acid, acrylic acid, crotonic acid, and allylacetic acid).

Specific examples of the monomer or oligomer having two or moredifferent polymerizable functional groups include reaction productsbetween vinyl group-containing carboxylic acids (e.g., methacrylic acid,acrylic acid, methacryloylacetic acid, acryloylacetic acid,methacryloylpropionic acid, acryloylpropionic acid, itaconyloylaceticacid, itaconyloylpropionic acid, and a carboxylic acid anhydride) andalcohols or amines, vinyl group-containing ester derivatives or amidederivatives (e.g., vinyl methacrylate, vinyl acrylate, vinyl itaconate,allyl methacrylate, allyl acrylate, allyl itaconate, vinylmethacryloylacetate, vinyl methacryloylpropionate, allylmethacryloylpropionate, vinyloxycarbonylmethyl methacrylate,vinyloxycarbonylmethyloxycarbonylethylene acrylate, N-allylacrylamide,N-allylmethacrylamide, N-allylitaconamide, and methacryloylpropionicacid allylamide) and condensation products between amino alcohols (e.g.,aminoethanol, 1-aminopropanol, 1-aminobutanol, 1-aminohexanol, and2-aminobutanol) and vinyl group-containing carboxylic acids.

The monomer or oligomer containing two or more polymerizable functionalgroups is used in an amount of not more than 10 mol %, and preferablynot more than 5 mol %, based on the total amount of monomer (a) andother monomers copolymerizable with monomer (a) to form the resin.

Where crosslinking between polymer molecules is conducted by theformation of chemical bonds upon the reaction of reactive groups in thepolymers according to the method (3), the reaction may be effected inthe same manner as usual reactions of organic low-molecular weightcompounds.

From the standpoint of obtaining mono-dispersed resin grains having anarrow size distribution and easily obtaining fine resin grains having adiameter of 0.5 μm or smaller, the method (2) using a polyfunctionalmonomer is preferred for the formation of network structure in thedispersion polymerization. Specifically, a monomer (a), a monomer (b)and/or a polymer (Pβ) and, in addition, a polyfunctional monomer (d) aresubjected to polymerization granulation reaction to obtain resin grains.Where the above-described polymer (Pβ) comprising the segment (β) isused, it is preferable to use a polymer (Pβ') which has a polymerizabledouble bond group copolymerizable with the monomer (a) in the side chainor at one terminal of the main chain of the polymer (Pβ).

The polymerizable double bond group is not particularly limited as faras it is copolymerizable with the monomer (a). Specific examples thereofinclude ##STR10## wherein p represents --H or --CH₃, and n represents 0or an integer of from 1 to 3.

The polymerizable double bond group may be bonded to the polymer chaineither directly or via a divalent organic residue. Specific examples ofthese polymers include those described, for example, in JP-A-61-43757,JP-A-1-257969, JP-A-2-74956, JP-A-1-282566, JP-A-2-173667, JP-A-3-15862,and JP-A-4-70669.

In the preparation of resin grains, the total amount of thepolymerizable compounds used is from about 5 to about 80 parts byweight, preferably from 10 to 50 parts by weight, per 100 parts byweight of the non-aqueous solvent. The polymerization initiator isusually used in an amount of from 0.1 to 5% by weight based on the totalamount of the polymerizable compounds. The polymerization is carried outat a temperature of from about 30+ to about 180° C., and preferably from40° to 120° C. The reaction time is preferably from 1 to 15 hours.

Now, an embodiment in which the resin (P) contains a photo- and/orheat-curable group or the resin (P) is used in combination with a photo-and/or heat-curable resin will be described below.

The polymer components containing at least one photo- and/orheat-curable group, which may be incorporated into the resin (P),include those described in the above-cited literature references. Morespecifically, the polymer components containing the above-describedpolymerizable functional group(s) can be used.

The content of the polymer component containing at least one photo-and/or heat-curable group in the block copolymer (P) ranges from 0.1 to40 parts by weight, and preferably from 1 to 30 parts by weight, basedon 100 parts by weight of the polymer segment (β) therein.

When the content is 0.1 part by weight or more, curing of thephotoconductive layer after film formation proceeds sufficiently,resulting in effective peeling off of the transfer layer. On the otherhand, when the content is 40 parts by weight or less, the goodelectrophotographic characteristics of the photoconductive layer areobtained without deterioration in reproducibility of original induplicated images and occurrence of background fog in non-image areas.

The photo- and/or heat-curable group-containing block copolymer (P) ispreferably used in an amount of not more than 40% by weight based on thetotal binder resin. In the range described above the goodelectrophotographic characteristics of the light-sensitive element areobtained.

The fluorine atom and/or silicon atom-containing resin may also be usedin combination with the photo- and/or heat-curable resin (D) in thepresent invention. Any of conventionally known curable resins may beused as the photo- and/or heat-curable resin (D). For example, resinscontaining the curable group as described with respect to the blockcopolymer (P) according to the present invention may be used.

Further, conventionally known binder resins for an electrophotographiclight-sensitive layer are employed. These resins are described, e.g., inTakaharu Shibata and Jiro Ishiwatari, Kobunshi, Vol. 17, p. 278 (1968),Harumi Miyamoto and Hidehiko Takei, Imaging, Vol. 1973, No. 8, KoichiNakamura (ed.), Kiroku Zairyoyo Binder no Jissai Gijutsu, Ch. 10, C.M.C.(1985), Denshishashin Gakkai (ed.), Denshishashinyo Yukikankotai noGenjo Symposium (preprint) (1985), Hiroshi Kokado (ed.), Saikin noKododenzairyo to Kankotai no Kaihatsu.Jitsuyoka, Nippon Kagaku Joho(1986), Denshishashin Gakkai (ed.), Denshishashin Gijutsu no Kiso ToOyo, Ch. 5, Corona (1988), D. Tatt and S. C. Heidecker, Tappi, Vol. 49,No. 10, p. 439 (1966), E. S. Baltazzi and R. G. Blanchlotte, et al.,Photo. Sci. Eng., Vol. 16, No. 5, p. 354 (1972), and Nguyen Chank Keh,Isamu Shimizu and Eiichi Inoue, Denshishashin Gakkaishi, Vol. 18, No. 2,p. 22 (1980).

Specific examples of these known binder resins used include olefinpolymers or copolymers, vinyl chloride copolymers, vinylidene chloridecopolymers, vinyl alkanoate polymers or copolymers, allyl alkanoatepolymers or copolymers, polymers or copolymers of styrene or derivativesthereof, butadiene-styrene copolymers, isoprene-styrene copolymers,butadiene-unsaturated carboxylic ester copolymers, acrylonitrilecopolymers, methacrylonitrile copolymers, alkyl vinyl ether copolymers,acrylic ester polymers or copolymers, methacrylic ester polymers orcopolymers, styrene-acrylic ester copolymers, styrene-methacrylic estercopolymers, itaconic diester polymers or copolymers, maleic anhydridecopolymers, acrylamide copolymers, methacrylamide copolymers, hydroxygroup-modified silicone resins, polycarbonate resins, ketone resins,polyester resins, silicone resins, amide resins, hydroxy group- orcarboxy group-modified polyester resins, butyral resins, polyvinylacetal resins, cyclized rubber-methacrylic ester copolymers, cyclizedrubber-acrylic ester copolymers, copolymers containing a heterocyclicring containing no nitrogen atom (the heterocyclic ring including furan,tetrahydrofuran, thiophene, dioxane, dioxofuran, lactone, benzofuran,benzothiophene and 1,3-dioxetane rings), and epoxy resins.

More specifically, reference can be made to Tsuyoshi Endo, NetsukokaseiKobunshi no Seimitsuka, C.M.C. (1986), Yuji Harasaki, Saishin BinderGijutsu Binran, Ch. II-1, Sogo Gijutsu Center (1985), Takayuki Otsu,Acryl Jushi no Gosei-Sekkei to Shinyoto Kaihatsu, Chubu Kei-ei KaihatsuCenter Shuppanbu (1985), and Eizo Omori, Kinosei Acryl-Kei Jushi, TechnoSystem (1985).

As described above, when the uppermost layer of light-sensitive element,for example, the overcoat layer or the photoconductive layer contains atleast one binder resin (B) and at least one block copolymer (P) formodifying the surface thereof, it is preferred that the layer furthercontains a small amount of photo- and/or heat-curable resin (D) and/or acrosslinking agent for further improving film curability.

The amount of photo- and/or heat-curable resin (D) and/or crosslinkingagent to be added is from 0.01 to 20% by weight, and preferably from 0.1to 15% by weight, based on the total amount of the binder resin (B) andthe block copolymer (P). In the range described above, the effect ofimproving film curability is obtained without adversely affecting theelectrophotographic characteristics.

A combined use of a crosslinking agent is preferable. Any of ordinarilyemployed crosslinking agents may be utilized. Suitable crosslinkingagents are described, e.g., in Shinzo Yamashita and Tosuke Kaneko (ed.),Kakyozai Handbook, Taiseisha (1981) and Kobunshi Gakkai (ed.), KobunshiData Handbook (Kisohen), Baifukan (1986). Specific examples of thecrosslinking agents include the compounds described as the crosslinkingagents above.

In addition, monomers containing a polyfunctional polymerizable group(e.g., vinyl methacrylate, acryl methacrylate, ethylene glycoldiacrylate, polyethylene glycol diacrylate, divinyl succinate, divinyladipate, diacryl succinate, 2-methylvinyl methacrylate,trimethylolpropane trimethacrylate, divinylbenzene, and pentaerythritolpolyacrylate) may also be used as the crosslinking agent.

As described above, the uppermost layer of the photoconductive layer[light-sensitive element] (a layer which will be in contact with thetransfer layer (X)) is preferably cured after film formation. It ispreferred that the binder resin (B), the block copolymer (P), thecurable resin (D), and the crosslinking agent to be used in thephotoconductiVe layer are so selected and combined that their functionalgroups easily undergo chemical bonding to each other.

Combinations of functional groups which easily undergo a polymerreaction are well known. Specific examples of such combinations areshown in Table 1 below, wherein a functional group selected from Group Acan be combined with a functional group selected from Group B. However,the present invention should not be construed as being limited thereto.

                  TABLE 1                                                         ______________________________________                                        Group A   Group B                                                             ______________________________________                                         ##STR11##                                                                               ##STR12##                                                                     ##STR13##                                                                     ##STR14##                                                                     ##STR15##                                                                     ##STR16##                                                                     ##STR17##                                                          ______________________________________                                    

In Table 1, R¹⁵ and R¹⁶ each represents an alkyl group; R¹⁷, R¹⁸, andR¹⁹ each represents an alkyl group or an alkoxy group, provided that atleast one of them is an alkoxy group; R represents a hydrocarbon group;B¹ and B² each represents an electron attracting group, e.g., --CN,--CF₃, --COR²⁰, --COOR²⁰, --SO₂ OR²⁰ (R²⁰ represents a hydrocarbongroup, e.g., --C_(n) H_(2n+1) (n: an integer of from 1 to 4), --CH₂ C₆H₅, or --C₆ H₅).

If desired, a reaction accelerator may be added to the binder resin foraccelerating the crosslinking reaction in the light-sensitive layer.

The reaction accelerators which may be used for the crosslinkingreaction forming a chemical bond between functional groups includeorganic acids (e.g., acetic acid, propionic acid, burytic acid,benzenesulfonic acid, and p-toluenesulfonic acid), phenols (e.g.,phenol, chlorophenol, nitrophenol, cyanophenol, bromophenol, naphthol,and dichlorophenol), organometallic compounds (e.g., zirconiumacetylacetonate, zirconium acetylacetone, cobalt acetylacetonate, anddibutoxytin dilaurate), dithiocarbamic acid compounds (e.g.,diethyldithiocarbamic acid salts), thiuram disulfide compounds (e.g.,tetramethylthiuram disulfide), and carboxylic acid anhydrides (e.g.,phthalic anhydride, maleic anhydride, succinic anhydride, butylsuccinicanhydride, benzophenone-3,3',4,4'-tetracarboxylic acid dianhydride, andtrimellitic anhydride). The reaction accelerators which may be used forthe crosslinking reaction involving polymerization includepolymerization initiators, such as peroxides and azobis compounds.

After a coating composition for the light-sensitive layer is coated, thebinder resin is cured by light and/or heat. Heat curing can be carriedout by drying under severer conditions than those for the production ofa conventional light-sensitive element. For example, elevating thedrying temperature and/or increasing the drying time may be utilized.After drying the solvent of the coating composition, the film ispreferably subjected to a further heat treatment, for example, at 60° to150° C. for 5 to 120 minutes. The conditions of the heat treatment maybe made milder by using the above-described reaction accelerator incombination.

Curing of the resin containing a photocurable functional group can becarried out by incorporating a step of irradiation of actinic ray intothe production line in the present invention. The actinic rays to beused include visible light, ultraviolet light, far ultraviolet light,electron beam, X-ray, γ-ray, and α-ray, with ultraviolet light beingpreferred. Actinic rays having a wavelength range of from 310 to 500 nmare more preferred. In general, a low-, high- or ultrahigh-pressuremercury lamp or a halogen lamp is employed as a light source. Usually,the irradiation treatment can be sufficiently performed at a distance offrom 5 to 50 cm for 10 seconds to 10 minutes.

Now, the second method for obtaining an electrophotographiclight-sensitive element having the surface of releasability by adsorbingor adhering the compound (S) for imparting the desired releasabilityonto the surface of a conventional electrophotographic light-sensitiveelement before the formation of the transfer layer (X) will be describedin detail below.

The compound (S) for imparting releasability is a compound containing atleast a fluorine and/or silicon atom and is not particularly limited inits structure as far as it can improve releasability of the surface ofelectrophotographic light-sensitive element, and includes a lowmolecular weight compound, an oligomer, and a polymer.

When the compound (S) is an oligomer or a polymer, the moiety having afluorine and/or silicon atom includes that incorporated into the mainchain of the oligomer or polymer and that contained as a substituent inthe side chain thereof. Of the oligomers and polymers, those containingrepeating units containing the moiety having a fluorine and/or siliconatom as a block are preferred since they advantageously adsorb on thesurface of electrophotographic light-sensitive element to impart goodreleasability.

The fluorine atom and/or silicon atom-containing moieties include thosedescribed with respect to the resin (A) used in the transfer layerabove.

Specific examples of the compound (S) containing a fluorine atom and/ora silicon atom which can be used in the present invention includefluorine and/or silicon-containing organic compounds described, forexample, in Tokiyuki Yoshida, et al. (ed.), Shin-ban KaimenkasseizaiHandbook, Kogaku Tosho (1987), Takao Karikome, Saishin KaimenkasseizaiOyo Gijutsu, C.M.C. (1990), Kunio Ito (ed.), Silicone Handbook, NikkanKogyo Shinbunsha (1990), Takao Karikome, Tokushukino Kaimenkasseizai,C.M.C. (1986), and A. M. Schwartz, et al., Surface Active Agents andDetergents, Vol. II.

Further, the compound (S) according to the present invention can besynthesized by utilizing synthesis methods as described, for example, inNobuo Ishikawa, Fussokagobutsu no Gosei to Kino, C.M.C. (1987), JiroHirano et al. (ed.), Ganfussoyukikagobutsu--Soho Gosei to Oyo, GijutsuJoho Kokai (1991), and Mitsuo Ishikawa, Yukikeiso Senryaku Shiryo,Chapter 3, Science Forum (1991).

Specific examples of polymer components having the fluorine atom and/orsilicon atom-containing moiety used in the oligomer or polymer includethe polymer components (F) described with respect to the resin (A)above.

When the compound (S) according to the present invention is a so-calledblock copolymer, the compound (S) may be any type of copolymer as far asit contains the fluorine atom and/or silicon atom-containing polymercomponents as a block. The term "to be contained as a block" means thatthe compound (S) has a polymer segment comprising at least 70% by weightof the fluorine atom and/or silicon atom-containing polymer componentbased on the weight of the polymer segment. The forms of blocks includean A-B type block, an A-B-A type block, a B-A-B type block, a graft typeblock, and a starlike type block as schematically illustrated withrespect to the resin (A) above. These block copolymers can besynthesized according to the methods described with respect to the resin(A) above.

In order to cause the compound (S) to adsorb or adhere to the surface ofelectrophotographic light-sensitive element, conventionally knownvarious methods can be employed. Methods which can be appropriatelyapplied to the apparatus used in the present invention are preferred.

For example, methods using an air doctor coater, a blade coater, a knifecoater, a squeeze coater, a dip coater, a reverse roll coater, atransfer roll coater, a gravure coater, a kiss roll coater, a spraycoater, a curtain coater, or a calender coater as described, forexample, in Yuji Harasaki, Coating Kogaku, Asakura Shoten (1971), YujiHarasaki, Coating Hoshiki, Maki Shoten (1979), and Hiroshi Fukada,Hot-melt Secchaku no Jissai Kobunshi Kankokai (1979) can be used.

A method wherein cloth, paper or felt impregnated with the compound (S)is pressed on the surface of light-sensitive element, a method ofpressing a curable resin impregnated with the compound (S), a methodwherein the light-sensitive element is wetted with a non-aqueous solventcontaining the compound (S) dissolved therein, and then dried to removethe solvent, and a method wherein the compound (S) dispersed in anon-aqueous solvent is migrated and adhered on the surface oflight-sensitive element by electrophoresis according to a wet-typeelectrodeposition method as described hereinafter can also be employed.

Further, the compound (S) can be applied on the surface oflight-sensitive element by utilizing a non-aqueous solvent containingthe compound (S) according to an ink jet method, followed by drying. Theink jet method can be performed with reference to the descriptions inShin Ohno (ed.), Non-impact Printing, C.M.C. (1986).

More specifically, a Sweet process or Hartz process of a continuous jettype, a Winston process of an intermittent jet type, a pulse jet processof an ink on-demand type, a bubble jet process, and a mist process of anink mist type are illustrated.

In any system, the compound (S) itself or diluted with a solvent isfilled in an ink tank or ink head cartridge in place of an ink to use.The solution of compound (S) used ordinarily has a viscosity of from 1to 10 cp and a surface tension of from 30 to 60 dyne/cm, and may containa surface active agent, or may be heated if desired. Although a diameterof ink droplet is in a range of from 30 to 100 μm due to a diameter ofan orifice of head in a conventional ink jet printer in order toreproduce fine letters, droplets of a larger diameter can also be usedin the present invention. In such a case, an amount of jet of thecompound (S) becomes large and thus a time necessary for the applicationcan be shortened. Further, to use multiple nozzles is very effective toshorten the time for application.

When silicone rubber is used as the compound (S), it is preferred thatsilicone rubber is provided on a metal axis to cover and the resultingsilicone rubber roller is directly pressed on the surface ofelectrophotographic light-sensitive element. In such a case, a nippressure is ordinarily in a range of from 0.5 to 10 Kgf/cm² and a timefor contact is ordinarily in a range of from 1 second to 30 minutes.Also, the light-sensitive element and/or silicone rubber roller may beheated up to a temperature of 150° C. According to this method, it isbelieved that a part of low molecular weight components contained insilicone rubber is moved from the silicone rubber roller onto thesurface of light-sensitive element during the press. The silicone rubbermay be swollen with silicone oil. Moreover, the silicone rubber may be aform of sponge and the sponge roller may be impregnated with siliconeoil or a solution of silicone surface active agent.

The application method of the compound (S) is not particularly limited,and an appropriate method can be selected depending on a state (i.e.,liquid, wax or solid) of the compound (S) used. A flowability of thecompound (S) can be controlled using a heat medium, if desired.

In accordance with the present invention, the surface ofelectrophotographic light-sensitive element is provided with the desiredreleasability by the adsorption or adhesion of the compound (S) thereto,and preferably exhibits the adhesive strength of not more than 150 g·fbefore the formation of transfer layer (X). The step for the applicationof compound (S) is not always necessary to conduct in a series of thesteps for the formation of a color image according to the presentinvention. The application may be suitably performed by an appropriatecombination of a light-sensitive element, an ability of a compound (S)for imparting the releasability and a means for the application.

An amount of the compound (S) adsorbed or adhered to the surface ofelectrophotographic light-sensitive element is not particularly limitedand is adjusted in a range wherein the electrophotographiccharacteristics of light-sensitive element do not adversely affected insubstance. Ordinarily, a thickness of the coating is sufficiently 1 μmor less. By the formation of weak boundary layer as defined in Bikerman,The Science of Adhesive Joints, Academic Press (1961), thereleasability-imparting effect of the present invention can be obtained.

Furthermore, the third method for obtaining an electrophotographiclight-sensitive element having a surface of releasability is a method ofconducting the impartation of releasability to the light-sensitiveelement simultaneously with the formation of transfer layer (X) on thelight-sensitive element by incorporating a compound (S) for impartingthe releasability into a dispersion for electrodeposition used for theformation of transfer layer (X) on the light-sensitive element accordingto the electrodeposition coating method.

Specifically, the peelable transfer layer (X) is formed by means ofelectrodeposition or adhesion of resin grains (AR) by electrophoresis onthe surface of electrophotographic light-sensitive element to form afilm using a dispersion for electrodeposition comprising resin grains(AR) having a glass transition point of not more than 140° C. or asoftening point of not more than 180° C. dispersed in an electricallyinsulating organic solvent having a dielectric constant of not more than3.5 and at least one compound (S) which has a fluorine atom and/or asilicon atom and is soluble at least 0.01 g per 1.0 liter of the organicsolvent.

The compound (S) for imparting releasability contained in the dispersionfor electrodeposition forming the transfer layer tends to adsorb oradhere onto the surface of light-sensitive element before theelectrodeposition or adhesion of dispersed resin grains (AR) byelectrophoresis on the surface of light-sensitive element, thelight-sensitive element having the releasability is consequentlyobtained at the formation of transfer layer (X). The method will bedescribed in more detail hereinafter.

The composition and material for the electrophotographic light-sensitiveelement which can be used in the present invention are not particularlylimited, and any of those conventionally known may be employed.

Suitable examples of electrophotographic light-sensitive element usedare described, for example, in R. M. Schaffert, Electrophotography,Forcal Press, London (1980), S. W. Ing, M. D. Tabak and W. E. Haas,Electrophotography Fourth International Conference, SPSE (1983), IsaoShinohara, Hidetoshi Tsuchida and Hideaki Kusakawa (ed.), Kirokuzairyoto Kankoseijushi, Gakkai Shuppan Center (1979), Hiroshi Kokado, Kagakuto Kogyo, Vol. 39, No. 3, p. 161 (1986), Saikin no Kododen Zairyo toKankotai no Kaihatsu.Jitsuyoka, Nippon Kagaku Joho Shuppanbu (1986),Denshishashin Gakkai (ed.), Denshishashin no Kiso to Oyo, Corona (1986),and Denshishashin Gakkai (ed.), Denshishashinyo Yukikankotai no GenjoSymposium (preprint), (1985). Specifically, the photoconductive layerincludes a single layer made of a photoconductive compound itself and aphotoconductive layer comprising a binder resin having dispersed thereina photoconductive compound. The dispersed type photoconductive layer mayhave a single layer structure or a laminated structure.

The photoconductive compounds used in the present invention may beinorganic compounds or organic compounds.

Inorganic photoconductive compounds used in the present inventioninclude those conventionally known for example, zinc oxide, titaniumoxide, zinc sulfide, cadmium sulfide, selenium, selenium-tellurium,silicon, lead sulfide. These compounds are used together with a binderresin to form a photoconductive layer, or they are used alone to form aphotoconductive layer by vacuum evaporation or spattering.

Where an inorganic photoconductive compound, e.g., zinc oxide ortitanium oxide, is used, a binder resin is usually used in an amount offrom 10 to 100 parts by weight, and preferably from 15 to 40 parts byweight, per 100 parts by weight of the inorganic photoconductivecompound.

As photoconductive layers using organic compounds, on the other hand,any of those conventionally known may be employed. Suitablephotoconductive layers containing an organic photoconductive compoundinclude a photoconductive layer mainly comprising an organicphotoconductive compound, a sensitizing dye, and a binder resin asdescribed, e.g., in JP-B-37-17162, JP-B-62-51462, JP-A-52-2437,JP-A-54-19803, JP-A-56-107246, and JP-A-57-161863; a layer mainlycomprising a charge generating agent, a charge transporting agent, and abinder resin as described, e.g., in JP-A-56-146145, JP-A-60-17751,JP-A-60-17752, JP-A-60-17760, JP-A-60-254142, and JP-A-62-54266; and adouble-layered structure containing a charge generating agent and acharge transporting agent in separate layers as described, e.g., inJP-A-60-230147, JP-A-60-230148, and JP-A-60-238853.

The photoconductive layer of the electrophotographic light-sensitiveelement according to the present invention may have any of theabove-described embodiments.

The organic photoconductive compounds which may be used in the presentinvention include (a) triazole derivatives described, e.g., in U.S. Pat.No. 3,112,197, (b) oxadiazole derivatives described, e.g., in U.S. Pat.No. 3,189,447, (c) imidazole derivatives described in JP-B-37-16096, (d)polyarylalkane derivatives described, e.g., in U.S. Pat. Nos. 3,615,402,3,820,989, and 3,542,544, JP-B-45-555, JP-B-51-10983, JP-A-51-93224,JP-A-55-108667, JP-A-55-156953, and JP-A-56-36656, (e) pyrazolinederivatives and pyrazolone derivatives described, e.g., in U.S. Pat.Nos. 3,180,729 and 4,278,746, JP-A-55-88064, JP-A-55-88065,JP-A-49-105537, JP-A-55-51086, JP-A-56-80051, JP-A-56-88141,JP-A-57-45545, JP-A-54-112637, and JP-A-55-74546, (f) phenylenediaminederivatives described, e.g., in U.S. Pat. No. 3,615,404, JP-B-51-10105,JP-B-46-3712, JP-B-47-28336, JP-A-54-83435, JP-A-54-110836, andJP-A-54-119925, (g) arylamine derivatives described, e.g., in U.S. Pat.Nos. 3,567,450, 3,180,703, 3,240,597, 3,658,520, 4,232,103, 4,175,961,and 4,012,376, JP-B-49-35702, West German Patent (DAS) 1,110,518,JP-B-39-27577, JP-A-55-144250, JP-A-56-119132, and JP-A-56-22437, (h)amino-substituted chalcone derivatives described, e.g., in U.S. Pat. No.3,526,501, (i) N,N-bicarbazyl derivatives described, e.g., in U.S. Pat.No. 3,542,546, (j) oxazole derivatives described, e.g., in U.S. Pat. No.3,257,203, (k) styrylanthracene derivatives described, e.g., inJP-A-56-46234, (l) fluorenone derivatives described, e.g., inJP-A-54-110837, (m) hydrazone derivatives described, e.g., in U.S. Pat.No. 3,717,462, JP-A-54-59143 (corresponding to U.S. Pat. No. 4,150,987),JP-A-55-52063, JP-A-55-52064, JP-A-55-46760, JP-A-55-85495,JP-A-57-11350, JP-A-57-148749, and JP-A-57-104144, (n) benzidinederivatives described, e.g., in U.S. Pat. Nos. 4,047,948, 4,047,949,4,265,990, 4,273,846, 4,299,897, and 4,306,008, (o) stilbene derivativesdescribed, e.g., in JP-A-58-190953, JP-A-59-95540, JP-A-59-97148,JP-A-59-195658, and JP-A-62-36674, (p) polyvinylcarbazole andderivatives thereof described in JP-B-34-10966, (q) vinyl polymers, suchas polyvinylpyrene, polyvinylanthracene,poly-2-vinyl-4-(4'-dimethylaminophenyl)-5-phenyloxazole, andpoly-3-vinyl-N-ethylcarbazole, described in JP-B-43-18674 andJP-B-43-19192, (r) polymers, such as polyacenaphthylene, polyindene, andan acenaphthylene-styrene copolymer, described in JP-B-43-19193, (s)condensed resins, such as pyrene-formaldehyde resin,bromopyrene-formaldehyde resin, and ethylcarbazole-formaldehyde resin,described, e.g., in JP-B-56-13940, and (t) triphenylmethane polymersdescribed in JP-A-56-90833 and JP-A-56-161550.

The organic photoconductive compounds which can be used in the presentinvention are not limited to the above-described compounds (a) to (t),and any of known organic photoconductive compounds may be employed inthe present invention. The organic photoconductive compounds may be usedeither individually or in combination of two or more thereof.

The sensitizing dyes which can be used in the photoconductive layerinclude those conventionally known as described, e.g., in Denshishashin,Vol. 12, p. 9 (1973) and Yuki Gosei Kagaku, Vol. 24, No. 11, p. 1010(1966). Specific examples of suitable sensitizing dyes include pyryliumdyes described, e.g., in U.S. Pat. Nos. 3,141,770 and 4,283,475,JP-A-48-25658, and JP-A-62-71965; triarylmethane dyes described, e.g.,in Applied Optics Supplement, Vol. 3, p. 50 (1969) and JP-A-50-39548;cyanine dyes described, e.g., in U.S. Pat. No. 3,597,196; and styryldyes described, e.g., in JP-A-60-163047, JP-A-59-164588, andJP-A-60-252517.

The charge generating agents which can be used in the photoconductivelayer include various conventionally known charge generating agents,either organic or inorganic, for example, selenium, seleniumtellurium,cadmium sulfide, zinc oxide, and organic pigments, for example, (1) azopigments (including monoazo, bisazo, and trisazo pigments) described,e.g., in U.S. Pat. Nos. 4,436,800 and 4,439,506, JP-A-47-37543,JP-A-58-123541, JP-A-58-192042, JP-A-58-219263, JP-A-59-78356,JP-A-60-179746, JP-A-61-148453, JP-A-61-238063, JP-B-60-5941, andJP-B-60-45664, (2) metal-free or metallized phthalocyanine pigmentsdescribed, e.g., in U.S. Pat. Nos. 3,397,086 and 4,666,802,JP-A-51-90827, and JP-A-52-55643, (3) perylene pigments described, e.g.,in U.S. Pat. No. 3,371,884 and JP-A-47-30330, (4) indigo or thioindigoderivatives described, e.g., in British Patent 2,237,680 andJP-A-47-30331, (5) quinacridone pigments described, e.g., in BritishPatent 2,237,679 and JP-A-47-30332, (6) polycyclic quinone dyesdescribed, e.g., in British Patent 2,237,678, JP-A-59-184348,JP-A-62-28738, and JP-A-47-18544, (7) bisbenzimidazole pigmentsdescribed, e.g., in JP-A-47-30331 and JP-A-47-18543, (8) squarylium saltpigments described, e.g., in U.S. Pat. Nos. 4,396,610 and 4,644,082, and(9) azulenium salt pigments described, e.g., in JP-A-59-53850 andJP-A-61-212542. These organic pigments may be used either individuallyor in combination of two or more thereof.

With respect to a mixing ratio of the organic photoconductive compoundand a binder resin, particularly the upper limit of the organicphotoconductive compound is determined depending on the compatibilitybetween these materials. The organic photoconductive compound, if addedin an amount over the upper limit, may undergo undesirablecrystallization. The lower the content of the organic photoconductivecompound, the lower the electrophotographic sensitivity. Accordingly, itis desirable to use the organic photoconductive compound in an amount asmuch as possible within such a range that crystallization does notoccur. In general, 5 to 120 parts by weight, and preferably from 10 to100 parts by weight, of the organic photoconductive compound is used per100 parts by weight of the total binder resins.

The binder resins (hereinafter referred to as binder resin (B)sometimes) which can be used in the light-sensitive element according tothe present invention include those for conventionally knownelectrophotographic light-sensitive elements. A weight average molecularweight of the binder resin is preferably from 5×10³ to 1×10⁶, and morepreferably from 2×10⁴ to 5×10⁵. A glass transition point of the binderresin is preferably from -40° to 200° C., and more preferably from -10°to 140° C. Binder resins which may be used in the present invention aredescribed, e.g., in Takaharu Shibata and Jiro Ishiwatari, Kobunshi, Vol.17, p. 278 (1968), Harumi Miyamoto and Hidehiko Takei, Imaging, Vol.1973, No. 8, Koichi Nakamura (ed.), Kiroku Zairyoyo Binder no JissaiGijutsu, Ch. 10, C.M.C. (1985), Denshishashin Gakkai (ed.),Denshishashinyo Yukikankotai no Genjo Symposium (preprint) (1985),Hiroshi Kokado (ed.), Saikin no Kododen Zairyo to Kankotai noKaihatsu.Jitsuyoka, Nippon Kagaku Joho (1986), Denshishashin Gakkai(ed.), Denshishashin Gijutsu no Kiso to Oyo, Ch. 5, Corona (1988), D.Tatt and S. C. Heidecker, Tappi, Vol. 49, No. 10, p. 439 (1966), E. S.Baltazzi and R. G. Blanchlotte, et al., Photo. Sci. Eng., Vol. 16, No.5, p. 354 (1972), and Nguyen Chank Keh, Isamu Shimizu and Eiichi Inoue,Denshi Shashin Gakkaishi, Vol. 18, No. 2, p. 22 (1980).

Specific examples of these known binder resins used include olefinpolymers or copolymers, vinyl chloride copolymers, vinylidene chloridecopolymers, vinyl alkanoate polymers or copolymers, allyl alkanoatepolymers or copolymers, polymers or copolymers of styrene or derivativesthereof, butadiene-styrene copolymers, isoprene-styrene copolymers,butadiene-unsaturated carboxylic ester copolymers, acrylonitrilecopolymers, methacrylonitrile copolymers, alkyl vinyl ether copolymers,acrylic ester polymers or copolymers, methacrylic ester polymers orcopolymers, styrene-acrylic ester copolymers, styrene-methacrylic estercopolymers, itaconic diester polymers or copolymers, maleic anhydridecopolymers, acrylamide copolymers, methacrylamide copolymers, hydroxygroup-modified silicone resins, polycarbonate resins, ketone resins,polyester resins, silicone resins, amide resins, hydroxy group- orcarboxy group-modified polyester resins, butyral resins, polyvinylacetal resins, cyclized rubber-methacrylic ester copolymers, cyclizedrubber-acrylic ester copolymers, copolymers containing a heterocyclicring containing no nitrogen atom (the heterocyclic ring including furan,tetrahydrofuran, thiophene, dioxane, dioxofuran, lactone, benzofuran,benzothiophene and 1,3-dioxetane rings), and epoxy resins.

Further, the electrostatic characteristics of the photoconductive layerare improved by using, as a binder resin (B) for a photoconductivesubstance, a resin having a relatively low molecular weight (e.g., aweight average molecular weight of from 10³ to 10⁴) and containing anacidic group such as a carboxy group, a sulfo group or a phosphonogroup. For instance, JP-A-63-217354 discloses a resin having polymercomponents containing an acidic group at random in the polymer mainchain, JP-A-64-70761 discloses a resin having an acidic group bonded atone terminal of the polymer main chain, JP-A-2-67563, JP-A-2-236561,JP-A-2-238458, JP-A-2-236562 and JP-A-2-247656 disclose a resin of grafttype copolymer having an acidic group bonded at one terminal of thepolymer main chain or a resin of graft type copolymer containing acidicgroups in the graft portion, and JP-A-3-181948 discloses an AB blockcopolymer containing acidic groups as a block.

Moreover, in order to obtain a satisfactorily high mechanical strengthof the photoconductive layer which may be insufficient by only using thelow molecular weight resin, a medium to high molecular weight resin ispreferably used together with the low molecular weight resin. Forinstance, JP-A-2-68561 discloses a thermosetting resin capable offorming crosslinked structures between polymers, JP-A-2-68562 disclosesa resin partially having crosslinked structures, and JP-A-2-69759discloses a resin of graft type copolymer having an acidic group bondedat one terminal of the polymer main chain. Also, in order to maintainthe relatively stable performance even when ambient conditions arewidely fluctuated, a specific medium to high molecular weight resin isemployed in combination. For instance, JP-A-3-29954, JP-A-3-77954,JP-A-3-92861 and JP-A-3-53257 disclose a resin of graft type copolymerhaving an acidic group bonded at the terminal of the graft portion or aresin of graft type copolymer containing acidic groups in the graftportion. Moreover, JP-A-3-206464 and JP-A-3-223762 discloses a grafttype copolymer having a graft portion formed from an AB block copolymercomprising an A block containing acidic groups and a B block containingno acidic group.

In a case of using these resins, the photoconductive substance isuniformly dispersed to form a photoconductive layer having goodsmoothness. Also, excellent electrostatic characteristics can bemaintained even when ambient conditions are fluctuated or when ascanning exposure system using a semiconductor laser beam is utilizedfor the image exposure.

The photoconductive layer usually has a thickness of from 1 to 100 μm,and preferably from 10 to 50 μm.

Where a photoconductive layer functions as a charge generating layer ofa laminated type light-sensitive element composed of a charge generatinglayer and a charge transporting layer, the charge generating layer has athickness of from 0.01 to 5 μm, and preferably from 0.05 to 2 μm.

Depending on the kind of a light source for exposure, for example,visible light or semiconductor laser beam, various dyes may be used asspectral sensitizers. The sensitizing dyes used include carbonium dyes,diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, phthaleindyes, polymethine dyes (including oxonol dyes, merocyanine dyes, cyaninedyes, rhodacyanine dyes, and styryl dyes), and phthalocyanine dyes(including metallized dyes), as described e.g., in Harumi Miyamoto andHidehiko Takei, Imaging, Vol. 1973, No. 8, p. 12, C. J. Young et al.,RCA Review, Vol. 15, p. 469 (1954), Kohei Kiyota et al., DenkitsushinGakkai Ronbunshi, Vol. J 63-C, No. 2, p. 97 (1980), Yuji Harasaki etal., Kogyo Kagaku Zasshi, Vol. 66, p. 78 and 188 (1963), and TadaakiTani, Nihon Shashin Gakkaishi, Vol. 35, p. 208 (1972).

Specific examples of carbonium dyes, triphenylmethane dyes, xanthenedyes, and phthalein dyes are described, e.g., in JP-B-51-452,JP-A-50-90334, JP-A-50-114227, JP-A-53-39130; JP-A-53-82353, U.S. Pat.Nos. 3,052,540 and 4,054,450, and JP-A-57-16456.

Usable polymethine dyes, such as oxonol dyes, merocyanine dyes, cyaninedyes, and rhodacyanine dyes, are described in F. M. Hamer, The CyanineDyes and Related Compounds. Specific examples of these dyes aredescribed, e.g., in U.S. Pat. Nos. 3,047,384, 3,110,591, 3,121,008,3,125,447, 3,128,179, 3,132,942, and 3,622,317, British Patents1,226,892, 1,309,274, and 1,405,898, JP-B-48-7814, and JP-B-55-18892.

Further, polymethine dyes capable of performing spectral sensitizationin the near infrared to infrared region of 700 nm or more include thosedescribed, e.g., in JP-A-47-840, JP-A-47-44180, JP-B-51-41061,JP-A-49-5034, JP-A-49-45122, JP-A-57-46245, JP-A-56-35141,JP-A-57-157254, JP-A-61-26044, JP-A-61-27551, U.S. Pat. Nos. 3,619,154and 4,175,956, and Research Disclosure, No. 216, pp. 117-118 (1982).

The light-sensitive element of the present invention is excellent inthat the characteristics thereof hardly vary with the combined use ofvarious sensitizing dyes.

If desired, the light-sensitive element may further contain variousadditives conventionally known for electrophotographic light-sensitiveelements. The additives include chemical sensitizers for increasingelectrophotographic sensitivity and plasticizers or surface activeagents for improving film properties.

Suitable examples of the chemical sensitizers include electronattracting compounds such as a halogen, benzoquinone, chloranil,fluoranil, bromanil, dinitrobenzene, anthraquinone,2,5-dichlorobenzoquinone, nitrophenol, tetrachlorophthalic anhydride,phthalic anhydride, maleic anhydride, N-hydroxymaleimide,N-hydroxyphthalimide, 2,3-dichloro-5,6-dicyanobenzoquinone,dinitrofluorenone, trinitrofluorenone, tetracyanoethylene, nitrobenzoicacid, and dinitrobenzoic acid; and polyarylalkane compounds, hinderedphenol compounds and p-phenylenediamine compounds as described in theliterature references cited in Hiroshi Kokado, et al., Saikin no KododenZairyo to Kankotai no Kaihatsu.Jitsuyoka, Chs. 4 to 6, Nippon KagakuJoho (1986). In addition, the compounds as described in JP-A-58-65439,JP-A-58-102239, JP-A-58-129439, and JP-A-62-71965 may also be used.

Suitable examples of the plasticizers, which may be added for improvingflexibility of a photoconductive layer, include dimethyl phthalate,dibutyl phthalate, dioctyl phthalate, diphenyl phthalate, triphenylphosphate, diisobutyl adipate, dimethyl sebacate, dibutyl sebacate,butyl laurate, methyl phthalyl glycolate, and dimethyl glycol phthalate.The plasticizer can be added in an amount that does not impairelectrostatic characteristics of the photoconductive layer. The amountof the additive to be added is not particularly limited, but ordinarilyranges from 0.001 to 2.0 parts by weight per 100 parts by weight of thephotoconductive substance.

The photoconductive layer of the present invention can be provided on aconventionally known support. In general, a support for anelectrophotographic light-sensitive layer is preferably electricallyconductive. The electrically conductive support which can be usedincludes a substrate (e.g., a metal plate, paper, or a plastic sheet)having been rendered conductive by impregnation with a low-resistantsubstance, a substrate whose back side (opposite to the light-sensitivelayer side). is rendered conductive and further having coated thereon atleast one layer for, for example, curling prevention, theabove-described substrate having formed on the surface thereof awater-resistant adhesive layer, the above-described substrate having onthe surface thereof at least one precoat layer, and a paper substratelaminated with a plastic film on which aluminum,etc. has been vacuumdeposited.

Specific examples of the conductive substrate and materials forrendering non-conductive substrates electrically conductive aredescribed, for example, in Yukio Sakamoto, Denshishashin, Vol. 14, No.1, pp. 2-11 (1975), Hiroyuki Moriga, Nyumon Tokushushi no Kagaku,Kobunshi Kankokai (1975), and M. F. Hoover, J. Macromol. Sci. Chem.,Vol. A-4, No. 6, pp. 1327-1417 (1970).

Now, the method of forming a color image according to the presentinvention will be described below.

First, the transfer layer (X) is formed on an electrophotographiclight-sensitive element having the surface of releasability.

According to the present invention, the formation of transfer layer (X)on a light-sensitive element can be performed in connection with thesteps of electrophotographic process and transfer or independentlytherefrom. Also, the transfer layer (X) may be previously formed or maybe formed each time on demand. When the transfer layer is previouslyformed independently from these steps, a conventional layer-formingmethod can be employed. For instance, a solution or dispersioncontaining the composition for the transfer layer is applied onto thesurface of light-sensitive element in a known manner.

The formation of transfer layer (X) is preferably performed each time inan apparatus in which the steps of electrophotographic process andtransfer are carried out. By such a method, the light-sensitive elementcan be repeatedly used in the same apparatus without throwing it awayafter using it only once. As a result, an advantage to reduce a cost ofduplicate can be obtained. For such a purpose, a hot-melt coatingmethod, transfer method or electrodeposition coating method ispreferably employed.

The hot-melt coating method will be described as one method for formingthe transfer layer in detail below.

The hot-melt coating method comprises hot-melt coating of thecomposition for the transfer layer by a known method. For such apurpose, a mechanism of a non-solvent type coating machine, for example,a hot-melt coating apparatus for a hot-melt adhesive (hot-melt coater)as described in the above-mentioned Hot-melt Secchaku no Jissai, pp. 197to 215 can be utilized with modification to suit with coating onto thelight-sensitive element drum. Suitable examples of coating machinesinclude a direct roll coater, an offset gravure roll coater, a rodcoater, an extrusion coater, a slot orifice coater, and a curtaincoater.

A melting temperature of the thermoplastic resin at coating is usuallyin a range of from 50° to 180° C., while the optimum temperature isdetermined depending on the composition of the thermoplastic resin to beused. It is preferred that the resin is first molten using a closedpre-heating device having an automatic temperature controlling means andthen heated in a short time to the desired temperature in a position tobe coated on the light-sensitive element. To do so can prevent fromdegradation of the thermoplastic resin upon thermal oxidation andunevenness in coating.

A coating speed may be varied depending on flowability of thethermoplastic resin at the time of being molten by heating, a kind ofcoater, and a coating amount, etc., but is suitably in a range of from 1to 100 mm/sec, preferably from 5 to 40 mm/sec.

The tansfer method will be described as one method for forming thetransfer layer in detail below.

The transfer method comprises previously forming a transfer layer onrelease paper by hot-melt coating, solvent coating or electrodepositionof latex, etc. and heat-transferring the transfer layer onto the surfaceof electrophotographic light-sensitive element.

The release paper having the transfer layer thereon is simply suppliedto an electrophotographic device in the form of a roll or sheet.

The release paper which can be employed in the present invention includethose conventionally known as described, for example, in Nenchaku(Nensecchaku) no Shin Gijutsu to Sono Yoto.Kakushu Oyoseihin no KaihatsuSiryo, published by Keiei Kaihatsu Center Shuppan-bu (May 20, 1978), andAll Paper Guide Shi no Shohin Jiten, Jo Kan, Bunka Sangyo Hen, publishedby Shigyo Times Sha (Dec. 1, 1983). Specifically, the release papercomprises a substrate such as nature Clupak paper laminated with apolyethylene resin, high quality paper pre-coated with asolvent-resistant resin, kraft paper, a PET film having an under-coatingor glassine having coated thereon a release agent mainly composed ofsilicone.

A solvent type of silicone is usually employed and a solution thereofhaving a concentration of from 3 to 7% by weight is coated on thesubstrate, for example, by a gravure roll or a wire bar, dried and thensubjected to heat treatment at not less than 150° C. to be cured. Thecoating amount is usually about 1 g/m².

Release paper for tapes, labels, formation industry use and cast coatindustry use each manufactured by a paper makingcompany and put on saleare also generally employed. Specific examples thereof include SeparateShi (manufactured by Oji Paper Co., Ltd.), King Rease (manufactured byShikoku Seishi K.K.), Sun Release (manufactured by Sanyo Kokusaku PulpK.K.) and NK High Release (manufactured by Nippon Kako Seishi K.K.).

In order to form the transfer layer on release paper, a composition forthe transfer layer mainly composed of resin is applied to releasingpaper in a conventional manner, for example, by bar coating, spincoating or spray coating to form a film.

For a purpose of heat transfer of the transfer layer on release paper toan electrophotographic light-sensitive element, conventional heattransfer methods are utilized. Specifically, release paper having thetransfer layer thereon is pressed on the electrophotographiclight-sensitive element to heat transfer the transfer layer.

The conditions for transfer of the transfer layer from release paper tothe surface of light-sensitive element are preferably as follows. A nippressure of the roller is from 0.1 to 10 kgf/cm² and more preferablyfrom 0.2 to 8 kgf/cm². A temperature at the transfer is from 25° to 100°C. and more preferably from 40° to 80° C. A speed of the transportationis from 0.5 to 100 mm/sec and more preferably from 3 to 50 mm/sec. Thespeed of transportation may differ from that of the electrophotographicstep or that of the heat transfer step of the transfer layer to areceiving material.

Now, the electrodeposition coating method will be described as onemethod for forming the transfer layer in detail below.

According to the electrodeposition coating method, the thermoplasticresin as described above is electrodeposited or adhered on the surfaceof light-sensitive element in the form of resin grains (AR) and thentransformed into a uniform thin film, for example, by heating, therebythe transfer layer (X) being formed.

The thermoplastic resin grains (AR) must have either a positive chargeor a negative charge. The electroscopicity of the resin grains isappropriately determined depending on a charging property of theelectrophotographic light-sensitive element to be used in combination.

An average grain diameter of the resin grains (AR) having the physicalproperty described above is generally in a range of from 0.01 to 15 μm,preferably from 0.05 to 5 μm and more preferably from 0.1 to 1 μm. Theresin grains may be employed as powder grains (in case of dry typeelectrodeposition) or grains dispersed in a non-aqueous system (in caseof wet type electrodeposition). The resin grains dispersed in anon-aqueous system are preferred since they can easily prepare thepeelable transfer layer having a uniform and small thickness.

In particular, the transferability of transfer layer formed is furtherimproved in case of using resin grains (ARW) containing in each grain atleast two kind of resins having a glass transition point different fromeach other, prefrably at least one of the resins (AH) having a highglass transition point described above and at least one of the resins(AL) having a low glass transition point described above.

The resin grains having a fine grain size used in the present inventioncan be produced by a conventionally known mechanical powdering method orpolymerization granulation method. These methods can be applied to theproduction of resin grains for both of dry type electrodeposition andwet type electrodeposition.

The mechanical powdering method for producing powder grains used in thedry type electrodeposition method includes a method wherein the resin isdirectly powdered by a conventionally known pulverizer to form finegrains (for example, a method using a ball mill, a paint shaker or a jetmill). If desired, mixing, melting and kneading of the materials forresin grains before the powdering and classification for a purpose ofcontrolling a grain diameter and after-treatment for treating thesurface of grain after the powdering may be performed in an appropriatecombination. A spray dry method is also employed.

Specifically, the powder grains can be easily produced by appropriatelyusing a method as described in detail, for example, in ShadanhojinNippon Funtai Kogyo Gijutsu Kyokai (ed.), Zoryu Handbook, II ed., OhmSha (1991), Kanagawa Keiei Kaihatsu Center, Saishin Zoryu Gijutsu noJissai, Kanagawa Keiei Kaihatsu Center Shuppan-bu (1984), and MasafumiArakawa et al (ed.), Saishin Funtai no Sekkei Gijutsu, Techno System(1988).

The polymerization granulation methods include conventionally knownmethods using an emulsion polymerization reaction, a seed polymerizationreaction or a suspension polymerization reaction each conducted in anaqueous system, or using a dispersion polymerization reaction conductedin a non-aqueous solvent system.

More specifically, grains are formed according to the methods asdescribed, for example, in Soichi Muroi, Kobunshi Latex no Kagaku,Kobunshi Kankokai (1970), Taira Okuda and Hiroshi Inagaki, Gosei JushiEmulsion, Kobunshi Kankokai (1978), soichi Muroi, Kobunshi Latex Nyumon,Kobunsha (1983), I. Purma and P. C. Wang, Emulsion Polymerization, I.Purma and J. L. Gaudon, ACS Symp. Sev., 24, p. 34 (1974), Fumio Kitaharaet al, Bunsan Nyukakei no Kagaku, Kogaku Tosho (1979), and Soichi Muroi(supervised), Chobiryushi Polymer no Saisentan Gijutsu, C.M.C. (1991),and then collected and pulverized in such a manner as described in thereference literatures cited with respect to the mechanical method above,thereby the resin grains being obtained.

In order to conduct dry type electrodeposition of the fine powder grainsthus-obtained, a conventionally known method, for example, a coatingmethod of electrostatic powder and a developing method with a dry typeelectrostatic developing agent can be employed. More specifically, amethod for electrodeposition of fine grains charged by a methodutilizing, for example, corona charge, triboelectrification, inductioncharge, ion flow charge, and inverse ionization phenomenon, asdescribed, for example, in J. F. Hughes, Seiden Funtai Toso, translatedby Hideo Nagasaka and Machiko Midorikawa, or a developing method, forexample, a cascade method, a magnetic brush method, a fur brush method,an electrostatic method, an induction method, a touchdown method and apowder cloud method, as described, for example, in Koich Nakamura (ed.),Saikin no Denshishashin Genzo System to Toner Zairyo noKaihatsu.Jitsuyoka, Ch. 1, Nippon Kogaku Joho (1985) is appropriatelyemployed.

The production of a latex in a non-aqueous system which are used in thewet type electrodeposition method can also be performed by any of themechanical powdering method and polymerization granulation method asdescribed above.

The mechanical powdering method includes a method wherein the resin isdispersed together with a dispersion polymer in a wet type dispersionmachine (for example, a ball mill, a paint shaker, Keddy mill, andDyno-mill), and a method wherein the materials for resin grains and adispersion assistant polymer (or a covering polymer) have beenpreviously kneaded, the resulting mixture is pulverized and then isdispersed together with a dispersion polymer. Specifically, a method ofproducing paints or electrostatic developing agents can be utilized asdescribed, for example, in Kenji Ueki (translated), Toryo no Ryudo toGanryo Bunsan, Kyoritsu Shuppan (1971), D. H. Solomon, The Chemistry ofOrganic Film Formers, John Wiley & Sons (1967), Paint and SurfaceCoating Theory and Practice, Yuji Harasaki, Coating Kogaku, AsakuraShoten (1971), and Yuji Harasaki, Coating no Kiso Kagaku, Maki Shoten(1977).

The polymerization granulation method includes a dispersionpolymerization method in a non-aqueous system conventionally known andis specifically described, for example, in Chobiryushi Polymer noSaisentan Gijutsu, Ch. 2, mentioned above, Saikin no Denshishashin GenzoSystem to Toner Zairyo no Kaihatsu.Jitsuyoka, Ch. 3, mentioned above,and K. E. J. Barrett, Dispersion Polymerization in Organic Media, JohnWiley & Sons (1975).

The resin grains (ARW) containing in each grain at least two kind ofresins having a glass transition point different from each otherdescribed above can be easily prepared using a seed polymerizationmethod. Specifically, fine grains of the resin (AL) or resin (AH) arefirst prepared by a conventionally known dispersion polymerizationmethod in a non-aqueous system and then using these fine grains asseeds, a monomer corresponding to the resin (AH) or resin (AL) issupplied to conduct polymerization in the same manner as above, wherebythe resin grains (ARW) are preferably obtained.

The resin grains composed of a random copolymer containing the polymercomponent (F) to increase the peelability of the resin (A) can be easilyobtained by performing a polymerization reaction using one or moremonomers forming the resin (A) which are soluble in an organic solventbut becomes insoluble therein by being polymerized together with amonomer corresponding to the polymer component (F) according to thepolymerization granulation method described above.

The resin grains containing the polymer component (F) as a block can beprepared by conducting a polymerization reaction using, as a dispersionstabilizing resins, a block copolymer containing the polymer component(F) as a block, or conducting polymerization reaction using amonofunctional macromonomer having a weight average molecular weight offrom 1×10³ to 2×10⁴, preferably from 3×10³ to 1.5×10⁴ and containing thepolymer component (F) as the main repeating unit together with one ormore monomers forming the resin (A). Alternatively, the resin grainscomposed of block copolymer can be obtained by conducting apolymerization reaction using a polymer initiator (for example, azobispolymer initiator or peroxide polymer initiator) containing the polymercomponent (F) as the main repeating unit.

As the non-aqueous solvent used in the dispersion polymerization methodin a non-aqueous system, there can be used any of organic solventshaving a boiling point of at most 200° C., individually or in acombination of two or more thereof.

Specific examples of the organic solvent include alcohols such asmethanol, ethanol, propanol, butanol, fluorinated alcohols and benzylalcohol, ketones such as acetone, methyl ethyl ketone, cyclohexanone anddiethyl ketone, ethers such as diethyl ether, tetrahydrofuran anddioxane, carboxylic acid esters such as methyl acetate, ethyl acetate,butyl acetate and methyl propionate, aliphatic hydrocarbons containingfrom 6 to 14 carbon atoms such as hexane, octane, decane, dodecane,tridecane, cyclohexane and cyclooctane, aromatic hydrocarbons such asbenzene, toluene, xylene and chlorobenzene, and halogenated hydrocarbonssuch as methylene chloride, dichloroethane, tetrachloroethane,chloroform, methylchloroform, dichloropropane and trichloroethane.However, the present invention should not be construed as being limitedthereto.

When the dispersed resin grains are synthesized by the dispersionpolymerization method in a non-aqueous solvent system, the average graindiameter of the dispersed resin grains can readily be adjusted to atmost 1 μm while simultaneously obtaining grains of mono-disperse systemwith a very narrow distribution of grain diameters.

A dispersive medium used for the resin grains dispersed in a non-aqueoussystem at the electrodeposition is usually a non-aqueous solvent havingan electric resistance of not less than 10⁸ Ω·cm and a dielectricconstant of not more than 3.5, since the dispersion is employed in amethod wherein the resin grains are electrodeposited utilizing a wettype electrostatic photographic developing process or electrophoresis inelectric fields.

The insulating solvents which can be used include straight chain orbranched chain aliphatic hydrocarbons, alicyclic hydrocarbons, aromatichydrocarbons, and halogen-substituted derivatives thereof. Specificexamples of the solvent include octane, isooctane, decane, isodecane,decalin, nonane, dodecane, isododecane, cyclohexane, cyclooctane,cyclodecane, benzene, toluene, xylene, mesitylene, Isopar E, Isopar G,Isopar H, Isopar L (Isopar: trade name of Exxon Co.), Shellsol 70,Shellsol 71 (Shellsol: trade name of Shell Oil Co.), Amsco OMS and Amsco460 Solvent (Amsco: trade name of Americal Mineral Spirits Co.). Theymay be used singly or as a combination thereof.

The insulating organic solvent described above is preferably employed asa non-aqueous solvent from the beginning of polymerization granulationof resin grains dispersed in the non-aqueous system. However, it is alsopossible that the granulation is performed in a solvent other than theabove-described insulating solvent and then the dispersive medium issubstituted with the insulating solvent to prepare the desireddispersion.

Another method for the preparation of a latex in non-aqueous system isthat a block copolymer comprising a polymer portion which is soluble inthe above-described non-aqueous solvent having an electric resistance ofnot less than 10⁸ Ω·cm and a dielectric constant of not more than 3.5and a polymer portion which is insoluble in the non-aqueous solvent, isdispersed in the non-aqueous solvent by a wet type dispersion method.Specifically, the block copolymer comprising a soluble polymer componentand an insoluble polymer component is first synthesized in an organicsolvent which dissolves the resulting block copolymer according to thesynthesis method of block copolymer as described above and thendispersed in the non-aqueous solvent described above.

In order to electrodeposit dispersed grains in a dispersive medium uponelectrophoresis, the grains must be electroscopic grains of positivecharge or negative charge. The impartation of electroscopicity to thegrains can be performed by appropriately utilizing techniques ondeveloping agents for wet type electrostatic photography. Morespecifically, it can be carried out using electroscopic materials andother additives as described, for example, in Saikin no DenshishashinGenzo System to Toner Zairyo no Kaihatsu.Jitsuyoka, pp. 139 to 148,mentioned above, Denshishashin Gakkai (ed.), Denshishashin Gijutsu noKiso to Oyo, pp. 497 to 505, Corona Sha (1988), and Yuji Harasaki,Denshishashin, Vol. 16, No. 2, p. 44 (1977).

Further, compounds as described, for example, in British Patents 893,429and 934,038, U.S. Pat. Nos. 1,122,397, 3,900,412 and 4,606,989,JP-A-60-179751, JP-A-60-185963 and JP-A-2-13965.

The latex in a non-aqueous system which can be employed forelectrodeposition usually comprises from 0.1 to 20 g of grainscontaining the thermoplastic resin, from 0.01 to 50 g of a dispersionstabilizing resin and if desired, from 0.0001 to 10 g of a chargecontrol agent in one liter of an electrically insulating dispersivemedium.

Furthermore, if desired, other additives may be added to the dispersionof resin grains in order to maintain dispersion stability and chargingstability of grains. Suitable examples of such additives include rosin,petroleum resins, higher alcohols, polyethers, silicone oil, paraffinwax and triazine derivatives. However, the present invention showed notbe construed as being limited thereto.

The total amount of these additives is restricted by the electricresistance of the dispersion. Specifically, if the electric resistanceof the dispersion becomes lower than 10⁸ Ω·cm, a sufficient amount ofthe thermoplastic resin grains deposited is reluctant to obtain and,hence, it is necessary to control the amounts of these additives in therange of not lowering the electric resistance than 10⁸ Ω·cm.

The thermoplastic resin grains which are prepared, provided with anelectrostatic charge and dispersed in an electrically insulting liquidbehave in the same manner as an electrophotographic wet type developingagent. For instance, the resin grains can be subjected toelectrophoresis on the surface of light-sensitive element using adeveloping device, for example, a slit development electrode device asdescribed in Denshishashin Gijutsu no Kiso to Oyo, pp. 275 to 285,mentioned above. Specifically, the grains comprising the thermoplasticresin are supplied between the electrophotographic light-sensitiveelement and an electrode placed in face of the light-sensitive element,and migrate by electrophoresis according to a potential gradient appliedfrom an external power source to adhere to or electrodeposit on theelectrophotographic light-sensitive element, thereby a film beingformed.

In general, if the charge of grains is positive, an electric voltage wasapplied between an electroconductive support of the light-sensitiveelement and a development electrode of a developing device from anexternal power source so that the light-sensitive material is negativelycharged, thereby the grains being electrostatically electrodeposited onthe surface of light-sensitive element.

Electrodeposition of grains can also be performed by wet type tonerdevelopment in a conventional electrophotographic process. Specifically,the light-sensitive element is uniformly charged and then subjected to aconventional wet type toner development without exposure to light orafter conducting a so-called print-off in which only unnecessary regionsare exposed to light, as described in Denshishashin Gijutsu no Kiso toOyo, pp. 46 to 79, mentioned above.

The amount of thermoplastic resin grain adhered to the light-sensitiveelement can be appropriately controlled, for example, by an externalbias voltage applied, a potential of the light-sensitive element chargedand a developing time.

After the electrodeposition of grains, the developing solution is wipedoff upon squeeze using a rubber roller, a gap roller or a reverseroller. Other known methods, for example, corona squeeze and air squeezecan also be employed. Then, the deposit is dried with cool air or warmair or by a infrared lamp preferably to be rendered the thermoplasticresin grains in the form of a film, thereby the transfer layer beingformed.

Further, the impartation of releasability and formation of transferlayer (X) onto a light-sensitive element can be performed at the sametime using a dispersion for electrodeposition to form the transfer layer(X) containing a compound (S) having at least a fluorine atom and/or asilicon atom at the formation of the transfer layer (X) on thelight-sensitive element according to the present invention. Thus, aconventional electrophotographic light-sensitive element can be utilizedwithout employing a specific means for imparting the releasability ontothe light-sensitive element.

The compound (S) used for such a purpose includes the same compound asdescribed with respect to the compound (S) for imparting releasabilityabove and is soluble at least 0.01 g per one liter of an electricallyinsulating organic solvent having a dielectric constant of not more than3.5 (at a temperature of 25° C.). By using the compound (S) which issoluble at least 0.01 g per liter of the electrically insulating organicsolvent, the stable releasability is constantly, provided on the surfaceof light-sensitive element without the occurrence of unevenness inadsorption of the compound (S).

Any compound (S) which has the property can be employed in that when asolution containing the compound (S) dissolved at a concentration of0.01 g per liter in an electrically insulating organic solvent describedabove is applied to an electrophotographic light-sensitive element to beused and set to touch, and then the resulting light-sensitive element ismeasured its adhesive strength according to JIS Z 0237-1980 "Testingmethods of pressure sensitive adhesive tapes and sheets" describedabove, the adhesive strength is not more than 150 g·f, preferably notmore than 100 g·f, and more preferably not more than 50 g·f. Specificexamples thereof are same as those described with respect to thecompound (S) above.

The amount of compound (S) added to the electrically insulating organicsolvent may be varied depending on the compound (S) and the electricallyinsulating organic solvent to be used. A suitable amount of the compound(S) is determined taking the effect to be obtained and adverse affectson electrophoresis of resin grains (e.g., decrease in electricresistance or increase in viscosity of the solution) into consideration.A preferred range of the compound (S) added is ordinarily from 0.01 to20 g per liter of electrically insulating organic solvent.

Then, toner images are formed on the transfer layer (X) provided on thesurface of electrophotographic light-sensitive element via aconventional electrophotographic process according to the presentinvention. Specifically, each step of charging, light exposure,development and fixing is performed in a conventionally known manner.

The developers which can be used in the present invention includeconventionally known developers for electrostatic photography, eitherdry type or liquid type developers for electrostatic photography.

For example, specific examples of the developer are described inDenshishashin Gijutsu no Kiso to Oyo, supra, pp. 497-505, KoichiNakamura (ed.), Toner Zairyo no Kaihatsuo.Jitsuyoka, Ch. 3, NipponKagaku Joho (1985), Gen Machida, Kirokuyo Zairyo to Kankosei Jushi, pp.107-127 (1983), and Denshishasin Gakkai (ed.), Imaging, Nos. 2-5,"Denshishashin no Genzo.Teichaku.Taiden.Tensha", Gakkai Shuppan Center.

Dry developers practically used include one-component magnetic toners,two-component toners, one-component non-magnetic toners, and capsuletoners. Any of these dry developers may be employed in the presentinvention.

Particularly, a combination of a scanning exposure system using a laserbeam based on digital information and a development system using aliquid developer is an advantageous process since the process isparticularly suitable to form highly accurate images. One specificexample of the formation of toner image is illustrated below.

An electrophotographic light-sensitive material is positioned on a flatbed by a register pin system and fixed on the flat bed by air suctionfrom the backside. Then it is charged by means of a charging device, forexample, the device as described in Denshishashin Gakkai (ed.),Denshishashin Gijutsu no Kiso to Oyo, p. 212 et seq., Corona Sha (Jun.15, 1988). A corotron or scotron system is usually used for the chargingprocess. In a preferred charging process, the charging conditions may becontrolled by a feedback system of the information on charged potentialfrom a detector connected to the light-sensitive material thereby tocontrol the surface potential within a predetermined range. Thereafter,the charged light-sensitive material is exposed to light by scanningwith a laser beam in accordance with the system described, for example,in ibidem, p. 254 et seq.

Toner development is then conducted using a liquid developer. Thelight-sensitive material charged and exposed is removed from the flatbed and developed according to a wet type developing method asdescribed, for example, in ibidem, p. 275 et seq. The exposure mode isdetermined in accord with the toner image development mode.Specifically, in case of reversal development, a negative image isirradiated with a laser beam, and a toner having the same chargepolarity as that of the charged light-sensitive material iselectrodeposited on the exposed area with a bias voltage applied. Forthe details, reference can be made to ibidem, p. 157 et. seq.

After the toner development, the light-sensitive material is squeezed toremove the excess developer as described in ibidem, p. 283 and dried.Preferably, the light-sensitive material may be rinsed with the carrierliquid used in the liquid developer alone before squeezing.

The typical liquid developer is basically composed of an electricallyinsulating organic solvent, for example, an isoparaffinic aliphatichydrocarbon (e.g., Isopar H or Isopar G (manufactured by Esso ChemicalCo.), Shellsol 70 or Shellsol 71 (manufactured by Shell Oil Co.) orIP-Solvent 1620 (manufactured by Idemitsu Petro-Chemical Co., Ltd.)) asa dispersion medium, having dispersed therein a colorant (e.g., aninorganic or organic dye or pigment) and a resin for impartingdispersion stability, fixability, and chargeability to the developer(e.g., an alkyd resin, an acrylic resin, a polyester resin, astyrene-butadiene resin, and rosin). If desired, the liquid developercan contain various additives for enhancing charging characteristics orimproving image characteristics.

The colorant is appropriately selected from known dyes and pigments, forexample, benzidine type, azo type, azomethine type, xanthene type,anthraquinone type, phthalocyanine type (including metallized type),titanium white, nigrosine, aniline black, and carbon black.

Other additives include, for example, those described in Yuji Harasaki,Denshishashin, Vol. 16, No. 2, p. 44, such asdi-2-ethylhexylsufosuccinic acid metal salts, naphthenic acid metalsalts, higher fatty acid metal salts, alkylbenzenesulfonic acid metalsalts, alkylphosphoric acid metal salts, lecithin, polyvinylpyrrolidone,copolymers containing a maleic acid monoamido component,coumarone-indene resins, higher alcohols, polyethers, polysiloxanes, andwaxes. However, the present invention should not be construed as beinglimited thereto.

With respect to the content of each of the main components of the liquiddeveloper, toner particles mainly comprising a resin (and, if desired, acolorant) are preferably present in an amount of from 0.5 to 50 parts byweight per 1000 parts by weight of a carrier liquid. If the tonercontent is less than 0.5 part by weight, the image density isinsufficient, and if it exceeds 50 parts by weight, the occurrence offog in the non-image areas may be tended to. If desired, theabove-described resin for dispersion stabilization which is soluble inthe carrier liquid is added in an amount of from about 0.5 to about 100parts by weight per 1000 parts by weight of the carrier liquid. Theabove-described charge control agent can be preferably added in anamount of from 0.001 to 1.0 part by weight per 1000 parts by weight ofthe carrier liquid. Other additives may be added to the liquiddeveloper, if desired. The upper limit of the total amount of otheradditives is determined, depending on electrical resistance of theliquid developer. Specifically, the amount of each additive should becontrolled so that the liquid developer exclusive of toner particles hasan electrical resistivity of not less than 10⁹ Ωcm. If the resistivityis less than 10⁹ Ωcm, a continuous gradation image of good quality canhardly be obtained.

The liquid developer can be prepared, for example, by mechanicallydispersing a colorant and a resin in a dispersing machine, e.g., a sandmill, a ball mill, a jet mill, or an attritor, to produce coloredparticles, as described, for example, in JP-B-35-5511, JP-B-35-13424,JP-B-50-40017, JP-B-49-98634, JP-B-58-129438, and JP-A-61-180248.

The colored particles may also be obtained by a method comprisingpreparing dispersed resin grains having a fine grain size and goodmonodispersity in accordance with a non-aqueous dispersionpolymerization method and coloring the resulting resin grains. In such acase, the dispersed grains prepared can be colored by dyeing with anappropriate dye as described, e.g., in JP-A-57-48738, or by chemicalbonding of the dispersed grains with a dye as described, e.g., inJP-A-53-54029. It is also effective to polymerize a monomer alreadycontaining a dye at the polymerization granulation to obtain adye-containing copolymer as described, e.g., in JP-B-44-22955.

Then, a transfer layer (Y) is formed on the surface bearing the tonerimage.

According to the present invention, the formation of transfer layer (Y)on the toner image can be performed independently from the steps ofelectrophotographic process and transfer or in an apparatus in whichthese steps are conducted. When the formation of transfer layer (Y) iscarried out independently from these steps, a conventional layer-formingmethod can be employed. For instance, a solution or dispersioncontaining the compositions for the transfer layer is applied onto thetoner image in a known manner.

The formation of transfer layer (Y) is preferably performed each time inan apparatus in which the steps of electrophotographic process andtransfer are carried out. By such a method, the light-sensitive elementcan be repeatedly used in the same apparatus without throwing it awayafter using it only once. As a result, an advantage to reduce a cost ofduplicate can be obtained. For such a purpose, a hot-melt coatingmethod, transfer method or electrodeposition coating method ispreferably employed.

A thickness of the transfer layer (Y) formed is preferably from 0.1 to10 μm, more preferably from 0.5 to 7 μm.

Specific embodiments of the above-described application methods are sameas those described with respect the formation of transfer layer (X)hereinbefore.

The toner image on the light-sensitive material is then heat-transferredto a receiving material together with the transfer layers (X) and (Y).The heat-transfer of the toner image can be performed using knownmethods and apparatus.

An example of the apparatus for transferring the transfer layers withthe toner image therebetween to a receiving material is illustrated inFIG. 2.

The apparatus is composed of a pair of rollers covered with rubber 4each containing therein a heating means 5 which are driven with apredetermined nip pressure applied. The surface temperature of rollers 4is preferably in a range of from 50° to 150° C., and more preferablyfrom 80° to 120° C., the nip pressure between rollers 4 is preferably ina range of from 0.2 to 20 kgf/cm², and more preferably from 0.5 to 10kgf/cm², and the transportation speed is preferably in a range of from0.1 to 300 mm/sec, and more preferably from 10 to 250 mm/sec. As amatter of course, these conditions should be optimized according to thephysical properties of the materials of the transfer layer,light-sensitive layer and support of the light-sensitive materialemployed.

The temperature of roller surface is preferably maintained within apredetermined range by means of known surface temperature detectivemeans 6 and temperature controller 7. A pre-heating means and a coolingmeans for the light-sensitive material may be provided in front of andat the rear of the heating roller portion, respectively.

Although not shown in FIG. 2, as a means for pressing two rollers, apair of springs provided at both ends of the shaft of at least oneroller or an air cylinder using compressed air may be employed.

It is preferred in the present invention that the transfer layers (X)and (Y) are formed on an electrophotographic light-sensitive elementwhose surface has the adhesive strength of not more than 150 g·f andtoner images, respectively, in an apparatus wherein anelectrophotographic process is performed, as described above. By such amethod, the light-sensitive element can be repeatedly used in withoutapparatus without throwing it away after using it only once, and theelectrophotographic process can be conducted continuously. As a result,an advantage to remarkably reduce a cost of duplicate formed can beobtained.

In order to form the transfer layer (X) on the surface of alight-sensitive element or to form the transfer layer (Y) on tonerimages in the apparatus wherein an electrophotographic process isconducted, the hot-melt coating method, transfer method orelectrodeposition coating method is preferably employed. The transferlayer (X) and transfer layer (Y) may be formed by the same method ordifferent methods.

A thickness of the transfer layer (X) formed is preferably from 0.1 to10 μm, more preferably from 0.5 to 7 μm.

The receiving material used in the present invention is not particularlylimited and any material conventionally known can be employed. Suitableexamples of the receiving materials include those of reflective type,for example, natural paper such as high quality paper, coated paper orart paper, synthetic paper, a metal plate such as an aluminum, iron orSUS plate, and those of transmittive type, for example, a plastic filmsuch as a polyester, polyolefin, polyvinyl chloride or polyacetate film.

Now, preferred embodiments of the method of forming a color imageaccording to the present invention will be described in greater detailwith reference to the accompanying drawings hereinbelow.

FIG. 3 is a schematic view of a color image-forming apparatus using thehot-melt coating method as a method for forming the transfer layer.

As described above, when an electrophotographic light-sensitive element11 whose surface has been modified to have releasability, a transferlayer 12 is formed on the light-sensitive element 11. On the other hand,when releasability of the surface of light-sensitive element 11 isinsufficient, a device is provided to cause the compound (S) to absorbor adhere to the surface of light-sensitive element before the formationof transfer layer 12, thereby the desired releasability being impartedto the surface of light-sensitive element 11. Specifically, the compound(S) is supplied from an applying device for compound (S) 30 whichutilizes any one of the embodiments as described above onto the surfaceof light-sensitive element 11. The applying device for compound (S) 30may be stationary or movable.

Thermoplastic resin 12a is coated on the surface of a light-sensitiveelement 11 provided on the peripheral surface of a drum by a hot-meltcoater 20 and is caused to pass under a suction/exhaust unit 15 to becooled to a predetermined temperature. After the hot-melt coater 20 ismoved to the stand-by position indicated as 20a, a liquid developingunit set 14 is moved to the position where the hot-melt coater 20 was.The unit set 14 is provided with a developing units 14y, 14m, 14c and14b containing yellow, magenta, cyan and black liquid developersrespectively. Each of the developing unit may be equipped with apre-bathing means, a rinsing means and a squeezing means in order toprevent the occurrence of stain in the non-image areas, if desired. Asthe pre-bath and the rinse solution, a carrier liquid for a liquiddeveloper is conventionally used.

The light-sensitive element 11 bearing thereon the transfer layer (X) 12composed of thermoplastic resin is then subjected to theelectrophotographic process. Specifically, when the light-sensitiveelement 11 is uniformly charged to, for instance, a positive polarity bya corona charger 18 and then is exposed imagewise by an exposure device(e.g., a semi-conductor laser) 19 on the basis of yellow imageinformation, the potential is lowered in the exposed regions and thus, acontrast in potential is formed between the exposed regions and theunexposed regions. The yellow liquid developing unit 14y containing aliquid developer comprising yellow pigment particles having a positiveelectrostatic charge dispersed in an electrically insulating liquid isbrought near the surface of a light-sensitive element 11 and is keptstationary with a gap of 1 mm therebetween.

The light-sensitive element 11 is first pre-bathed by a pre-bathingmeans provided in the developing unit, and then the yellow liquiddeveloper is supplied on the surface of the light-sensitive elementwhile applying a developing bias voltage between the light-sensitiveelement and a development electrode by a bias voltage source and wiring(not shown). The bias voltage is applied so that it is slightly lowerthan the surface potential of the unexposed regions, while thedevelopment electrode is charged to positive and the light-sensitiveelement is charged to negative. When the bias voltage applied is toolow, a sufficient density of the toner image cannot be obtained.

The liquid developer adhering to the surface of light-sensitive elementis subsequently washed off by a rinsing means installed in thedeveloping unit 14 and the rinse solution adhering to the surface of thelight-sensitive material is removed by a squeeze means. Then, thelight-sensitive material is dried by passing under the suction/exhaustunit 15. The above described electrophotographic process is repeatedwith respect to each image information of magenta, cyan and black.Meanwhile a heat transfer means 17 is kept away from the surface of thelight-sensitive element.

After four color images are formed on the transfer layer (X) 12, atransfer layer (Y) 13 is provided on the four color toner images in thesame manner as the transfer layer. (X) 12 described above.

Then, the transfer layer is pre-heated in a predetermined range by apre-heating means 17a for heat transfer, pressed against a rubber roller17b having therein a heater with a temperature control means with thereceiving material 16 intervening therebetween, and then passed under acooling roller 17c, thereby heat-transferring the toner images to thereceiving material 16 together with the transfer layer (X) 12 andtransfer layer (Y) 13. Thus a cycle of steps is terminated.

The heat transfer means 17 for heating-transferring the transfer layer(X) 12 and transfer layer (Y) 13 to the receiving material 16 comprisesthe pre-heating means 17a, the heating roller 17b which is in the formof a metal roller having therein a heater and is covered with rubber,and the cooling roller 17c. As the pre-heating means 17a, a non-contacttype heater such as an infrared line heater, a flash heater or the likeis used, and the transfer layer is pre-heated in a range below atemperature of the surface of the light-sensitive element achieved withheating by the heating roller 17b. The surface temperature oflight-sensitive element heated by the heating roller 17b is preferablyin a range of from 50° to 150° C., and more preferably from 80° to 120°C.

The cooling roller 17c comprises a metal roller which has a good thermalconductivity such as aluminum, copper or the like and is covered withsilicone rubber. It is preferred that the cooling roller 17c is providedwith a cooling means therein or on a portion of the outer surface whichis not brought into contact with the receiving material in order toradiate heat. The cooling means includes a cooling fan, a coolantcirculation or a thermoelectric cooling element, and it is preferredthat the cooling means is coupled with a temperature controller so thatthe temperature of the cooling roller 17c is maintained within apredetermined range.

The nip pressure of the rollers is preferably in a range of from 0.2 to20 kgf/cm² and more preferably from 0.5 to 15 kgf/cm². Although notshown, the rollers may be pressed by springs provided on opposite endsof the roller shaft or by an air cylinder using compressed air.

A speed of the transportation is preferably in a range of from 0.1 to100 mm/sec and more preferably in a range of from 1 to 30 mm/sec. Thespeed of transportation may differ between the electrophotographic stepand the heat transfer step.

By stopping the apparatus in the state where the transfer layer has beenformed, the next operation can start with the electrophotographicprocess. Thus, the transfer layer acts to protect the light-sensitiveelement and prevent the properties of the light-sensitive element fromdeteriorating due to environmental influence.

It is needless to say that the above-described conditions should beoptimized depending on the physical properties of the light-sensitivematerial (i.e., the transfer layer, the light-sensitive layer andsupport) and the receiving material employed. Especially it is importantto determine the conditions of pre-heating, roller heating and coolingin the heat transfer step taking into account the factors such as glasstransition point, softening temperature, flowability, tackiness, filmproperties and film thickness of the transfer layer. Specifically, theconditions should be set so that the tackiness of the transfer layerincreases and the transfer layer is closely adhered to the receivingmaterial when the transfer layer softened to a certain extent by thepre-heating means passes the heating roller, and so that the temperatureof the transfer layer is decreased to reduce the flowability and thetackiness after the transfer layer subsequently passes the coolingroller and thus the transfer layer is peeled as a film from the surfaceof the light-sensitive element together with the toner.

A device for simply forming a transfer layer utilizing release paper ona light-sensitive element is schematically illustrated in FIG. 5.

In FIG. 5, release paper 10 having provided thereon a transfer layer (X)12 is heat-pressed on the light-sensitive element 11 by a heating roller117b, thereby the transfer layer (X) 12 being transferred on the surfaceof light-sensitive element 11. The release paper 10 is cooled by acooling roller 117c and recovered. The light-sensitive element 11 isheated by a pre-heating means 17a to improve transferability of thetransfer layer (X) 12 upon heat-press, if desired.

One example of specific embodiment of an apparatus for conducting theelectrophotographic process and the heat-transfer onto a receivingmaterial in which a device for forming a transfer layer by transferringfrom release paper is installed is schematically illustrated in FIG. 4.

The apparatus of FIG. 4 has essentially the same constitution as theapparatus (FIG. 3) using the hot-melt coating method described aboveexcept for a transfer means 117 for forming a transfer layer (X) 12 ortransfer layer (Y) 13.

In FIG. 4, the transfer layer (X) 12 is transferred from release paper10 to a light-sensitive element, a toner image is formed on the transferlayer (X) by an electrophotographic process, and the transfer layer (Y)is formed on the toner image in the same manner as the formation oftransfer layer (X) using the transfer mean 117. Then, the transfer means117 is substituted with a transfer means 17 having a receiving material16, and heat-transfer is conducted in the same manner as described withrespect to the hot-melt coating method above. Alternatively, both atransfer means for transferring the transfer layer (X) 12 and transferlayer (Y) 13 from release paper 10 onto the light-sensitive element 11and a transfer means for transferring the transfer layer (X) 12 andtransfer layer (Y) 13 having a toner image therebetween onto thereceiving material 16 are installed in the apparatus.

The conditions for transfer of the transfer layer (X) 12 from releasepaper 10 to the surface of light-sensitive element 11 are preferably asfollows. A nip pressure of the roller is from 0.1 to 10 kgf/cm² and morepreferably from 0.2 to 8 kgf/cm². A temperature at the transfer is from25° to 100° C. and more preferably from 40° to 80° C. A speed of thetransportation is from 0.5 to 100 mm/sec and more preferably from 3 to50 mm/sec. The speed of transportation may differ from that of theelectrophotographic step or that of the heat transfer step of thetransfer layer to a receiving material.

The formation of transfer layer by the electrodeposition coating methodwill be described in greater detail with reference to the accompanyingdrawings below. FIG. 6 is a schematic view of an electrophotographictransfer image-forming apparatus having installed therein a device forforming a transfer layer by the electrodeposition coating method. Theapparatus of FIG. 6 has essentially the same constitution as theapparatus using the hot-melt coating method described above except for ameans for forming a transfer layer (X) 12 or transfer layer (Y) 13.

A dispersion 12b of thermoplastic resin grains is supplied to anelectrodeposition unit 14T provided in a movable liquid developing unitset 14. The electrodeposition unit 14T is first brought near the surfaceof the light-sensitive element 11 and is kept stationary with a gap of 1mm between a development electrode of the electrodeposition unit 14 andthe light-sensitive element. The light-sensitive element 11 is rotatedwhile supplying the dispersion 12b of thermoplastic resin grains intothe gap and applying an electric voltage across the gap from an externalpower source (not shown), whereby the grains are deposited over theentire image-forming areas of the surface of the light-sensitive element11.

The dispersion 12b of thermoplastic resin grains excessively adhered tothe surface of the light-sensitive element 11 is removed by a squeezingdevice built in the electrodeposition unit 14T, and the light-sensitiveelement is dried by passing under the suction/exhaust unit 15. Then thethermoplastic resin grains are fused by the pre-heating means 17a andthus a transfer layer (X) 12 in the form of thermoplastic resin film isobtained.

Thereafter the transfer layer is cooled to a predetermined temperature,if desired, from an outside of the light-sensitive element or from aninside of the drum of the light-sensitive element by a cooling devicewhich is similar to the suction/exhaust unit 15, although not shown.After moving away the electrodeposition unit 14T, the liquid developingunit set 14 is posited. After the formation of toner image, a transferlayer (Y) 13 is formed thereon in the same manner as the transfer layer(X) 12 described above.

When the formation of transfer layer (X) and formation of transfer layer(Y) are conducted in an apparatus wherein an electrophotographic processis carried out and the light-sensitive element 11 is repeatedlyemployed, the transfer layer (X) and transfer layer (Y) which may havethe same composition or different compositions from each other areprovided by appropriately moving the same device for forming transferlayer. When transfer layers having different compositions are provided,two devices for forming transfer layer may be utilized. In such a case,the same process for forming transfer layer or a combination ofdifferent processes for forming transfer layer may be used.Specifically, the device(s) are appropriately designed so as to bepositioned at the formation of transfer layer in place of other processunit in an apparatus for electrophotographic process.

Preferred embodiments of the present invention include the following.

(1) A method of forming a color image comprising forming at least onecolor toner image on a first peelable transfer layer provided on thesurface of an electrophotographic light-sensitive element whose surfacehas releasability by an electrophotographic process, forming a secondtransfer layer on the toner image and transferring the toner imagetogether with the first transfer layer and the second transfer layeronto a receiving material.

(2) The method of forming a color image as described in (1) above,wherein the surface of electrophotographic light-sensitive element hasan adhesive strength measured according to JIS Z 0237-1980 "Testingmethods of pressure sensitive adhesive tapes and sheets" of not morethan 150 gram·force.

(3) The method of forming a color image as described in (1) or (2)above, wherein the first transfer layer and the second transfer layermainly contain a thermoplastic resin having a glass transition point ofnot more than 140° C. or a softening point of not more than 180° C.

(4) The method of forming a color image as described in (3) above,wherein the first transfer layer mainly contains a thermoplastic resin(AH) having a glass transition point of from 10° C. to 140° C. or asoftening point of from 35° C. to 180° C. and the second transfer layermainly contains a thermoplastic resin (AL) having a glass transitionpoint of not more than 45° C. or a softening point of not more than 60°C. in which a difference in the glass transition point or softeningpoint between the thermoplastic resin (AH) and the thermoplastic resin(AL) is at least 2° C.

(5) The method of forming a color image as described in (1) above,wherein the transfer layer is formed by at least one of a hot-meltcoating method, an electrodeposition coating method and a transfermethod.

(6) The method of forming a color image as described in (1) above,wherein the transfer layer is formed by electrodepositing orelectrostatically adhering grains mainly contain a thermoplastic resingrain (ARW) having a glass transition point of not more than 140° C. ora softening point of not more than 180° C. and containing at least onethermoplastic resin having a glass transition point of from 10° C. to140° C. or a softening point of from 35° C. to 180° C. and at least onethermoplastic resin having a glass transition point of not more than 45°C. or a softening point of not more than 60° C.

(7) The method of forming a color image as described in (1) above,wherein the electrophotographic light-sensitive element contains apolymer having a polymer component containing at least one of a siliconatom and a fluorine atom in its surface region adjacent to the firsttransfer layer.

(8) The method of forming a color image as described in (1) above,wherein the electrophotographic light-sensitive element is caused byadsorption or adherence of a compound (S) containing at least a fluorineatom and/or a silicon atom onto its surface.

(9) The method of forming a color image as described in (1) above,wherein the first transfer layer is formed by means of electrodepositionor adhesion of resin grains (AR) by electrophoresis on the surface ofelectrophotographic light-sensitive element to form a film using adispersion-for electrodeposition comprising resin grains (AR) having aglass transition point of not more than 140° C. or a softening point ofnot more than 180° C. dispersed in an electrically insulating organicsolvent having a dielectric constant of not more than 3.5 and at leastone compound (S) which has a fluorine atom and/or a silicon atom and issoluble at least 0.01 g per 1.0 liter of the organic solvent.

(10) The method of forming a color image as described in (9) above,wherein the resin grains (AR) are supplied between theelectrophotographic light-sensitive element and an electrode placed inface of the light-sensitive element and migrated by electrophoresisaccording to a potential gradient applied from an external power sourceto adhere to or electrodeposit on the electrophotographiclight-sensitive element, to thereby form a film.

(11) The method of forming a color image as described in (1) above,wherein the receiving material has a thermoplastic resin layer on itsside to come into contact with the transfer layer.

(12) A method of forming a color image comprising performing thefollowing steps (i) to (iv) in the same apparatus:

(i) a step of forming a first peelable transfer layer on anelectrophotographic light-sensitive element,

(ii) a step of forming at least one color toner image on the firsttransfer layer by an electrophotographic process,

(iii) a step of forming a second peelable transfer layer on the tonerimage, and

(iv) a step of transferring the toner image together with the firsttransfer layer and the second transfer layer onto a receiving material.

(13) The method of forming a color image as described in (12) above,wherein the following step (a) is performed before the step (i) in thesame apparatus.

(a) a step of causing a compound (S) containing at least one of afluorine atom and a silicon atom to adsorb or adhere onto the surface ofelectrophotographic light-sensitive element.

(14) An apparatus for forming a color image comprising a means forforming a first peelable transfer layer on the surface of anelectrophotographic light-sensitive element, a means for forming atleast one color toner image on the transfer layer by anelectrophotographic process, a means for forming a second peelabletransfer layer on the toner image formed on the first transfer layer anda means for transferring the toner image together with the firsttransfer layer and the second transfer layer onto a receiving material.

(15) The apparatus for forming a color image as described in (14) above,which further comprises a means for causing a compound (S) containing atleast one of a fluorine atom and a silicon atom to adsorb or adhere ontothe surface of electrophotographic light-sensitive element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view for explanation of the method according tothe present invention.

FIG. 2 is a schematic view of a device for heat-transfer of transferlayer to a receiving material.

FIG. 3 is a schematic view of a transfer apparatus using a hot-meltcoating method for the formation of transfer layer.

FIG. 4 is a schematic view of a transfer apparatus using a transfermethod for the formation of transfer layer.

FIG. 5 is a schematic view of a device for the formation of transferlayer on a light-sensitive element utilizing release paper.

FIG. 6 is a schematic view of a transfer apparatus using anelectrodeposition coating method for the formation of transfer layer.

FIG. 7 is a schematic view of a device for applying a compound (S).

Explanation of the Symbols:

1 Support of light-sensitive element

2 Light-sensitive layer

3 Toner image

4 Roller covered with rubber

5 Heating means

6 Surface temperature detective means

7 Temperature controller

10 Release paper

11 Light-sensitive element

12 Transfer layer (X)

13 Transfer layer (Y)

14 Liquid developing unit set

14T Electrodeposition unit

14y Yellow liquid developing unit

14m Magenta liquid developing unit

14c Cyan liquid developing unit

14b Black liquid developing unit

15 Suction/exhaust unit

15a Suction part

15b Exhaust part

16 Receiving material

17 Heat transfer means

17a Pre-heating means

17b Heating roller

17c Cooling roller

18 Corona charger

19 Exposure device

20 Hot-melt coater

20a Stand-by position of hot-melt coater

30 Applying unit for compound (S)

117 Heat transfer means

117b Heating roller

117c Cooling roller

120 Transfer roll

121 Metering roll

122 Compound (S)

BEST MODE FOR CONDUCTING THE INVENTION

The present invention is illustrated in greater detail with reference tothe following examples, but the present invention is not to be construedas being limited thereto.

Synthesis Examples of Resin Grain (ARH) for Transfer Layer:

SYNTHESIS EXAMPLE 1 OF RESIN GRAIN (ARH): (ARH-1)

A mixed solution of 10 g of Dispersion Stabilizing Resin (Q-1) havingthe structure shown below, 100 g of vinyl acetate, and 384 g of Isopar Hwas heated to a temperature of 70° C. under nitrogen gas stream whilestirring. To the solution was added 0.8 g of2,2'-azo-bis(isovaleronitrile) (abbreviated as AIVN) as a polymerizationinitiator, followed by reacting for 3 hours. Twenty minutes after theaddition of the polymerization initiator, the reaction mixture becamewhite turbid, and the reaction temperature rose to 88° C. Then, 0.5 g ofthe above-described initiator was added to the reaction mixture, thereaction were carried out for 2 hours. The temperature was raised to100° C. and stirred for 2 hours to remove the unreacted vinyl acetate bydistillation. After cooling, the reaction mixture was passed through anylon cloth of 200 mesh to obtain a white dispersion which was a latexof good monodispersity with a polymerization ratio of 90% and an averagegrain diameter of 0.23 μm. The grain diameter was measured by CAPA-500manufactured by Horiba Ltd.

A part of the white dispersion was centrifuged at a rotation of 1×10⁴r.p.m. for 60 minutes and the resin grains precipitated were collectedand dried. A weight average molecular weight (Mw) and a glass transitionpoint (Tg) of the resin grain were measured (Mw and Tg of resin grainbeing measured in the same manner hereinafter).

Mw: 2×10⁵ (measured by a GPC method and calculated in terms ofpolystyrene)

Tg: 38° C. ##STR18##

SYNTHESIS EXAMPLE 2 OF RESIN GRAIN (ARH): (ARH-2)

A mixed solution of 15 g of Dispersion Stabilizing Resin (Q-2) havingthe structure shown below, 65 g of benzyl methacrylate, 35 g of methylacrylate, 1.3 g of methyl 3-mercaptopropionate and 552 g of isopar H washeated to a temperature of 50° C. under nitrogen gas stream whilestirring. To the solution was added 1 g of2,2'-azobis(2-cyclopropylpropionitrile) (abbreviated as ACPP) as apolymerization initiator, followed by reacting for 2 hours. To thereaction mixture was added 0.8 g of ACPP, followed by reacting for 2hours. Further, 0.8 g of AIVN was added thereto and the reactiontemperature was adjusted to 75° C., and the reaction was continued for 3hours. Then, the temperature was raised to 90° C., and the untreatedmonomers were distilled off under a reduced pressure of 20 to 30 mm Hg.After cooling the reaction mixture was passed through a nylon cloth of200 mesh to obtain a white dispersion which was a latex of goodmonodispersity with a polymerization ratio of 98% and an average graindiameter of 0.20 μm. An Mw of the resin grain was 2.8×10⁴ and a Tgthereof was 48° C. ##STR19##

SYNTHESIS EXAMPLE 3 OF RESIN GRAIN (ARH): (ARH-3)

A mixed solution of 14 g of Dispersion Stabilizing Resin (Q-3) havingthe structure shown below and 382 g of isopar G was heated to atemperature of 50° C. under nitrogen gas stream while stirring. To thesolution was added dropwise a mixture of 75 g of benzyl methacrylate, 25g of 2-ethylhexyl methacrylate and 0.8 g of ACPP over a period of onehour, followed by reacting for one hour. To the reaction mixture wasfurther added 0.8 g of ACPP, followed by reacting for 2 hours. Then, 0.8g of AIVN was added thereto and the temperature was adjusted to 80° C.,and the reaction was continued for 2 hours. To the reaction mixture wasfurther added 0.5 g of AIVN, followed by reacting for 2 hours. Then, thetemperature was raised to 100° C., and the unreacted monomers weredistilled off under a reduced pressure of 10 to 20 mm Hg. After cooling,the reaction mixture was passed through a nylon cloth of 200 mesh toobtain a white dispersion which was a latex of good monodispersity witha polymerization ratio of 90% and an average grain diameter of 0.17 μm.An Mw of the resin grain was 1×10⁵ and a Tg thereof was 45° C. ##STR20##

SYNTHESIS EXAMPLE 4 OF RESIN GRAIN (ARH): (ARH-4)

A mixed solution of 14 g of Dispersion Stabilizing Resin (Q-4) havingthe structure shown below, 10 g of a monofunctional macromonomer ofdimethylsiloxane (Macromonomer (M-1)) (Placcel FM-0725 manufactured ofChisso Corp.; a weight average molecular weight (Mw): 1×10⁴) and 553 gof Isopar H was heated to a temperature of 50° C. under nitrogen gasstream while stirring. To the solution was added dropwise a mixture of70 g of methyl methacrylate, 20 g of ethyl acrylate, 2.6 g of methyl3-mercaptopropionate and 1.0 g of ACPP over a period of 30 minutes,followed by reacting for 1.5 hours. To the reaction mixture was furtheradded 0.8 g of ACPP, followed by reacting for 2 hours. Then, 0.8 g ofAIVN was added thereto and the temperature was adjusted to 80° C., andthe reaction was continued for 2 hours. To the reaction mixture wasfurther added 0.5 g of ACPP, followed by reacting for 2 hours. Aftercooling, the reaction mixture was passed through a nylon cloth of 200mesh to obtain a white dispersion which was a latex of goodmonodispersity with a polymerization ratio of 99% and an average graindiameter of 0.15 μm. An Mw of the resin grain was 9×10³ and a Tg thereofwas 40° C. ##STR21##

SYNTHESIS EXAMPLES 5 TO 8 OF RESIN GRAIN (ARH): (ARH-5) TO (ARH-8)

Each of the resin grains (ARH-5) to (ARH-8) was synthesized in the samemanner as in Synthesis Examples 4 of Resin Grain (ARH) except for usingeach of the macromonomers (Mw thereof being in a range of from 8×10³ to1×10⁴) shown in Table 2 below in place of 10 g of Macromonomer (M-1)employed in Synthesis Example 4 of Resin Grain (ARH). A polymerizationratio of each of the resin grains was in a range of from 98 to 99% andan average grain diameter thereof was in a range of from 0.15 to 0.25 μmwith good monodispersity of a narrow size distribution. An Mw of each ofthe resin grains was in a range of from 2.5×10⁴ to 4×10⁴ and a Tgthereof was in a range of from 40° C. to 70° C.

                                      TABLE 2                                     __________________________________________________________________________    Synthesis                                                                     Example of                                                                             Resin                                                                Resin Grain (ARH)                                                                      Grain (ARH)                                                                         Macromonomer                                                   __________________________________________________________________________    5        ARH-5                                                                                ##STR22##                                                     6        ARH-6                                                                                ##STR23##                                                     7        ARH-7                                                                                ##STR24##                                                     8        ARH-8                                                                                ##STR25##                                                     __________________________________________________________________________

SYNTHESIS EXAMPLE 9 OF RESIN GRAIN (ARH): (ARH-9)

A mixture of 5 g of coarse powder of a styrene-butadiene copolymer(48/52 ratio by weight) (Sorprene 303 manufactured by Asahi Kasei KogyoKabushiki Kaisha) having a softening point of 45° C. pulverized by atrio-blender, 4 g of a dispersion stabilizing resin (Sorprene 1205manufactured by Asahi Kasei Kogyo Kabushiki Kaisha) and 51 g of Isopar Hwas dispersed in a paint shaker (manufactured by Toyo Seiki SeisakushoCo.) with glass beads having a diameter of about 4 mm for 20 minutes.The resulting pre-dispersion was subjected to a wet type dispersionprocess using Dyno-mill KDL (manufactured by Sinmaru Enterprises Co.,Ltd.) with glass beads having a diameter of from 0.75 to 1 mm at arotation of 4500 r.p.m. for 6 hours, and then passed through a nyloncloth of 200 mesh to obtain a white dispersion which was a latex havingan average grain diameter of 0.4 μm.

SYNTHESIS EXAMPLES 1 TO 16 OF RESIN GRAIN (ARL): (ARL-1) TO (ARL-16)

Each of the resin grains (ARL) was synthesized in the same manner as inSynthesis Example 3 of Resin Grain (ARH) except for using each of themonomers shown in Table 3 below in place of 75 g of benzyl methacrylateand 25 g of 2-ethylhexyl methacrylate employed in Synthesis Example 3 ofResin Grain (ARH). A polymerization ratio of each of the whitedispersions obtained was in a range of from 90 to 99% and an averagegrain diameter thereof was in a range of from 0.13 to 0.20 μm with goodmonodispersity. A Tg of each of the resin grains was in a range of from10° C. to 50° C.

                  TABLE 3                                                         ______________________________________                                        Synthesis                                                                     Example of                                                                    Resin   Resin                                                                 Grain (ARL)                                                                           Grain (ARL)                                                                             Monomer                                                     ______________________________________                                        1       ARL-1     Vinyl acetate       80 g                                                      Vinyl propionate    20 g                                    2       ARL-2     Vinyl acetate       85 g                                                      Vinyl butyrate      15 g                                    3       ARL-3     Vinyl acetate       90 g                                                      Vinyl laurate       10 g                                    4       ARL-4     Phenethyl methacrylate                                                                            70 g                                                      Methyl acrylate     30 g                                                      3-Phenylpropyl methacrylate                                                                       75 g                                    5       ARL-5     Ethyl acrylate      25 g                                    6       ARL-6     Methyl methacrylate 65 g                                                      2-Butoxyethyl methacrylate                                                                        35 g                                    7       ARL-7     Benzyl methacrylate 60 g                                                      2,3-Dipropoxypropyl methacrylate                                                                  40 g                                    8       ARL-8     Vinyl acetate       95 g                                                      N-Vinylpyrrolidone  5 g                                     9       ARL-9     Benzyl methacrylate 75 g                                                      Ethylene glycol monomethylether                                                                   25 g                                                      monomethacrylate                                            10      ARL-10    2-Phenyl-2-methylethyl methacrylate                                                               75 g                                                      Methyl acrylate     25 g                                    11      ARL-11    Methyl methacrylate 60 g                                                      Methyl acrylate     40 g                                    12      ARL-12    Styrene             70 g                                                      Vinyl toluene       30 g                                    13      ARL-13    Methyl methacrylate 65 g                                                      Octadeyl methacrylate                                                                             35 g                                    14      ARL-14    Methyl methacrylate 65 g                                                      Ethyl methacrylate  30 g                                                      Macromonomer FMO-725                                                                              5 g                                     15      ARL-15    Vinyl acetate       97 g                                                      Crotonic acid       3 g                                     16      ARL-16    Methyl methacrylate 60 g                                                      Ethyl acrylate      35 g                                                      N-Methylacrylamide  5 g                                     ______________________________________                                    

SYNTHESIS EXAMPLE 1 OF RESIN GRAIN (AR): (AR-1)

A mixed solution of 20 g of Dispersion Stabilizing Resin (Q-1) havingthe structure described above, 40 g of methyl methacrylate, 60 g ofmethyl acrylate, 1.3 g of methyl 3-mercaptopropionte and 542 g of IsoparH was heated to a temperature of 60° C. under nitrogen gas stream whilestirring. To the solution was added 0.8 g of2,2'-azobis(isovaleronitrile) (abbreviated as AIVN) as a polymerizationinitiator, followed by reacting for 2 hours. Twenty minutes after theaddition of the polymerization initiator, the reaction mixture becamewhite turbid, and the reaction temperature rose to 88° C. Then, 0.5 g ofthe above-described initiator was added to the reaction mixture, thereaction were carried out for 2 hours, and 0.3 g of the initiator wasfurther added thereto, followed by reacting for 3 hours. After cooling,the reaction mixture was passed through a nylon cloth of 200 mesh toobtain a white dispersion which was a latex of good monodispersity witha polymerization ratio of 99% and an average grain diameter of 0.18 μm.The grain diameter was measured by CAPA-500 manufactured by Horiba Ltd.

A mixed solution of the whole amount of the above-described resin graindispersion (as seed) and 10 g of Dispersion Stabilizing Resin (Q-1) washeated to a temperature of 60° C. under nitrogen gas stream withstirring. To the mixture was added dropwise a mixture of 85 g of benzylmethacrylate, 15 g of methyl acrylate, 1.0 g of methyl3-mercaptopropionate, 0.8 g of AIVN and 200 g of Isopar H over a periodof 2 hours, followed by further reacting for 2 hours. Then 0.8 g of AIVNwas added to the reaction mixture, the temperature thereof was raised to70° C., and the reaction was conducted for 2 hours. Further, 0.6 g ofAIVN was added thereto, followed by reacting for 3 hours. After cooling,the reaction mixture was passed through a nylon cloth of 200 mesh toobtain a white dispersion which was a latex of good monodispersityhaving a polymerization ratio of 98% and an average grain diameter of0.25 μm.

In order to investigate that the resin grain thus-obtained was composedof the two kind of resins, the state of resin grain was observed using ascanning electron microscope (SEM).

Specifically, the dispersion of Resin Grain (AR-1) was applied to apolyethylene terephthalate film so that the resin grains were present ina dispersive state on the film, followed by heating at a temperature of45° C. or 70° C. for 5 minutes to prepare a sample. Each sample wasobserved using a scanning electron microscope (JSL-T330 Typemanufactured by JEOL Co., Ltd.) of 20,000 magnifications. As a result,the resin grains were observed with the sample heated at 45° C. On thecontrary, with the sample heated at 70° C. the resin grains had beenmelted by heating and were not observed.

The state of resin grain was observed in the same manner as describedabove with respect to resin grains formed from respective two kind ofresins (copolymers) constituting Resin Grain (AR-1), i.e., ComparativeResin Grains (1) and (2) described below and a mixture of ComparativeResin Grains (1) and (2) in a weight ratio of 1:1. As a result, it wasfound that with Comparative Resin Grain (1), the resin grains were notobserved in the sample heated at 45° C., although the resin grains wereobserved in the sample before heating. On the other hand, withComparative Resin Grain (2), the resin grains were not observed in thesample heated at 70° C. Further, with the mixture of two kind of resingrains, disappearance of the resin grains was observed in the sampleheated at 45° C. in comparison with the sample before heating.

From these results it was confirmed that Resin Grain (AR-1) describedabove was not a mixture of two kind of resin grains but contained twokind of resins therein, and had a core/shell structure wherein the resinhaving a relatively high Tg formed shell portion and the resin having arelatively low Tg formed core portion.

The structure of resin grains (AR) is not particularly limited andincludes a core/shell structure composed of the resin (AH) having arelatively high Tg and the resin (AL) having a relatively low Tg asdescribed above, a core/shell structure composed of a combination of aninverse order of the resins or a structure composed of a mixture of theresins without localization.

Preparation of Comparative Resin Grain (1)

A mixed solution of 10 g of Dispersion Stabilizing Resin (Q-1), 20 g ofmethyl methacrylate, 30 g of methyl acrylate, 0.65 g of methyl3-mercaptopriopionate and 329 g of Isopar H was heated to a temperatureof 60° C. under nitrogen gas stream while stirring. To the solution wasadded 0.4 g of AIVN as a polymerization initiator, followed by reactingfor 2 hours. Twenty minutes after the addition of the polymerizationinitiator, the reaction mixture became white turbid, and the reactiontemperature rose to 88° C. Then, 0.2 g of AIVN was added to the reactionmixture, the reaction were carried out for 2 hours, and 0.3 g of AIVNwas added thereto, followed by reacting for 3 hours. After cooling, thereaction mixture was passed through a nylon cloth of 200 mesh to obtaina white dispersion which was a latex of good monodispersity with apolymerization ratio of 99% and an average grain diameter of 0.25 μm. ATg of the resin grain thus-obtained was 38° C.

Preparation of Comparative Resin Grain (2)

The same procedure as in Preparation of Comparative Resin Grain (1)described above was repeated except for using a mixed solution of 10 gof Dispersion Stabilizing Resin (Q-1) described above, 42.5 g of benzylmethacrylate, 7.5 g of methyl acrylate, 0.5 g of methyl3-mercaptopropionate and 326 g of Isopar H. The white dispersionthus-obtained was a latex of good monodispersity with a polymerizationratio of 98% and an average grain diameter of 0.24 μm. A Tg of the resingrain was 65° C.

SYNTHESIS EXAMPLE 2 OF RESIN GRAIN (AR): (AR-2)

(1) Synthesis of Dispersion Stabilizing Resin (Q-5)

A mixed solution of 99.5 g of dodecyl methacrylate, 0.5 g ofdivinylbenzene and 200 g of toluene was heated to a temperature of 80°C. under nitrogen gas stream while stirring. To the solution was added 2g of 2,2'-azobis(isobutyronitrile) (abbreviated as AIBN), followed byreacting for 3 hours, then further was added 0.5 g of AIBN, the reactionwas carried out for 4 hours. The solid content of the resultingcopolymer was 33.3% by weight, and an Mw thereof was 4×10⁴.

(2) Synthesis of Resin Grain

A mixed solution of 18 g (solid basis) of Dispersion Stabilizing Resin(Q-5) described above, 80 g of vinyl acetate, 20 g of vinyl propionateand 382 g of Isopar H was heated to a temperature of 80° C. undernitrogen gas stream while stirring. To the solution was added 1.6 g ofAIVN, followed by reacting for 1.5 hours, then was added 0.8 g of AIVN,followed by reacting for 2 hours. Further, 0.5 g of AIVN was added tothe reaction mixture, the reaction were carried out for 3 hours. Thetemperature was raised to 100° C. and stirred for 2 hours to remove theunreacted monomers by distillation. After cooling, the reaction mixturewas passed through a nylon cloth of 200 mesh to obtain a whitedispersion which was a latex of good monodispersity with apolymerization ratio of 87% and an average grain diameter of 0.17 μm.

A mixture of the whole amount of the above-described resin graindispersion (as seed) and 20 g of Dispersion Stabilizing Resin (Q-5) washeated to a temperature of 60° C. under nitrogen gas stream withstirring. To the mixture was added dropwise a mixture of 65 g of methylmethacrylate, 35 g of butyl methacrylate, 2.6 g of methyl3-mercaptopropionate, 0.8 g of AIVN and 200 g of Isopar H over a periodof 2 hours, followed by reacting for one hour. Then 0.8 g of AIVN wasadded to the reaction mixture, the temperature thereof was raised to 75°C., and the reaction was conducted for 2 hours. Further, 0.6 g of AIVNwas added thereto, followed by reacting for 3 hours. After cooling, thereaction mixture was passed through a nylon cloth of 200 mesh to obtaina white dispersion which was a latex of good monodispersity having apolymerization ratio of 98% and an average grain diameter of 0.23 μm.

SYNTHESIS EXAMPLE 3 OF RESIN GRAIN (AR): (AR-3)

A mixed solution of 25 g of Dispersion Stabilizing Resin (Q-3) havingthe structure described above and 546 g of Isopar H was heated to atemperature of 60° C. under nitrogen gas stream while stirring. To thesolution was added dropwise a mixture of 65 g of benzyl methacrylate, 35g of ethyl methacrylate, 1.8 g of 2-mercaptoethanol, 1.0 of AIVN and 200g of Isopar H over a period of one hour, followed by further reactingfor one hour. To the mixture was added 0.8 g of AIVN, followed byreacting for 2 hours, then 0.5 g of AIVN was added to the reactionmixture, the temperature thereof was raised to 80° C., and the reactionwas conducted for 2 hours. Further, 0.5 g of AIBN was added thereto,followed by reacting for 3 hours. After cooling, the reaction mixturewas passed through a nylon cloth of 200 mesh to obtain a whitedispersion which was a latex of good monodispersity having apolymerization ratio of 98% and an average grain diameter of 0.17 μm.

A mixture of the whole amount of the above-described resin graindispersion (as seed) and 15 g of Dispersion Stabilizing Resin (Q-3) washeated to a temperature of 60° C. under nitrogen gas stream withstirring. To the mixture was added dropwise a mixture of 80 g of methylmethacrylate, 20 g of hexyl methacrylate, 2 g of 3-mercaptopropionicacid, 0.8 g of AIVN and 564 g of Isopar H over a period of 2 hours,followed by further reacting for 2 hours. Then 0.8 g of AIBN as apolymerization initiator was added to the reaction mixture, thetemperature thereof was raised to 80° C., and the reaction was conductedfor 2 hours. Further, 0.6 g of AIBN was added thereto, followed byreacting for 3 hours. After cooling, the reaction mixture was passedthrough a nylon cloth of 200 mesh to obtain a white dispersion which wasa latex of good monodispersity having a polymerization ratio of 98% andan average grain diameter of 0.24 μm.

SYNTHESIS EXAMPLE 4 OF RESIN GRAIN (AR): (AR-4)

A mixed solution of 15 g of Dispersion Stabilizing Resin (Q-4), 60 g ofmethyl methacrylate, 40 g of 2,3-dipropionyloxypropy methacrylate, 2.0 gof methyl 3-mercaptopropionate and 549 g of Isopar H was heated to atemperature of 60° C. under nitrogen gas stream while stirring. To thesolution was added 0.8 g of AIVN as a polymerization initiator, followedby reacting for 2 hours. Twenty minutes after the addition of thepolymerization initiator, the reaction mixture became white turbid, andthe reaction temperature rose to 88° C. Then, 0.5 g of AIVN was added tothe reaction mixture, the reaction were carried out for 2 hours, and 0.3g of AIVN was further added thereto, followed by reacting for 3 hours.After cooling, the reaction mixture was passed through a nylon cloth of200 mesh to obtain a white dispersion which was a latex of goodmonodispersity with a polymerization ratio of 98% and an average graindiameter of 0.18 μm.

A mixture of 260 g of the above-described resin grain dispersion (asseed), 14 g of Dispersion Stabilizing Resin (Q-1), 10 g of Macromonomer(M-1) having the structure shown below and 553 g of Isopar H was heatedto a temperature of 55° C. under nitrogen gas stream while stirring. Tothe solution was added dropwise a mixture of 60 g of benzylmethacrylate, 30 g of 3-phenyl methacrylate, 2 g of methyl3-mercatoporopionate, 1.0 g of 2,2'-azobis(2-cyclopropylpropionitrile)(abbreviated as ACPP) and 200 g of Isopar H over a period of one hour,followed by reacting for one hour with stirring. To the reaction mixturewas added 0.8 g of ACPP, followed by reacting for 2 hours. Further, 0.5g of AIVN was added thereto and the reaction temperature was adjusted to80° C., and the reaction was continued for 3 hours. After cooling thereaction mixture was passed through a nylon cloth of 200 mesh to obtaina white dispersion which was a latex of good monodispersity with apolymerization ratio of 97% and an average grain diameter of 0.24 μm.##STR26##

SYNTHESIS EXAMPLES 5 TO 10 OF RESIN GRAIN (AR): (AR-5) TO (AR-10)

Each latex dispersion was prepared according to a wet type dispersionprocess in the same manner as in Synthesis Example 9 of Resin Grain(ARH) except for using each of the compounds shown in Table 4 below inplace of Sorprene 303 as the resin (R) employed in Synthesis Example 9of Resin Grain (AR). An average grain diameter of each of the dispersionobtained was in a range of from 0.35 to 0.5 μm.

                  TABLE 4                                                         ______________________________________                                        Synthesis                                                                     Example of                                                                    Resin   Resin                                                                 Grain (AR)                                                                            Grain (AR)                                                                              Resin (A)                                                   ______________________________________                                        5       AR-5      Ethylene/methacrylic acid copolymer                                           (96.4:3.6 by molar ratio)                                                     (Nimacrel N-699 manufactured by DuPont-                                       Mitsui Polychemicals Co., Ltd.)                             6       AR-6      Ethylene/vinyl acetate copolymer                                              (Evaflex 420 manufactured by DuPont-                                          Mitsui Polychemicals Co., Ltd.)                             7       AR-7      Ethylene/ethyl acrylate copolymer                                             (Evalfex-EEA, A-703 manufactured by DuPont-                                   Mitsui Polychemicals Co., Ltd.)                             8       AR-8      Vinyl chloride/vinyl acetate copolymer                                        (UCAR-VYHH manufactured by Union                                              Carbide Co., Ltd.)                                          9       AR-9      Cellulose acetate butyrate                                                    (Cellidor Bsp. manufactured by Bayer AG)                    10       AR-10    Polyvinyl butyral resin                                                       (S-Lec manufactured by Sekisui Chemical                                       Co., Ltd.)                                                  ______________________________________                                    

Synthesis Examples of Resin (P):

SYNTHESIS EXAMPLE 1 OF RESIN (P): (P-1)

A mixed solution of 80 g of methyl methacrylate, 20 g of adimethylsiloxane macromonomer (Macromonomer (M-1)) (Placcel FM-0725manufactured by Chisso Corp.; Mw: 1×10⁴), and 200 g of toluene washeated to a temperature of 75° C. under nitrogen gas stream. To thesolution was added 1.0 g of AIBN, followed by reacting for 4 hours. Tothe mixture was further added 0.7 g of AIBN, and the reaction wascontinued for 4 hours. An Mw of the copolymer thus-obtained was 5.8×10⁴(as measured by a GPC method). ##STR27##

SYNTHESIS EXAMPLES 2 TO 9 OF RESIN (P): (P-2) TO (P-9)

Each of copolymers was synthesized in the same manner as in SynthesisExample 1 of Resin (P), except for replacing methyl methacrylate andMacromonomer (M-1) (Placcel FM-0725) used in Synthesis Example 1 ofResin (P) with each monomer corresponding to the polymer component shownin Table 5 below. An Mw of each of the resulting polymers was in a rangeof from 4.5×10⁴ to 6×10⁴.

                                      TABLE 5                                     __________________________________________________________________________     ##STR28##                                                                    Syn-                                                                          thesis                                                                        Exam-                                                                         ple of                                                    x/y/z               Resin                                                                            Resin                                                  (weight             (P)                                                                              (P)                                                                              R   Y              b   W         Z                  ratio)              __________________________________________________________________________    2  P-2                                                                              C.sub.2 H.sub.5                                                                    ##STR29##     CH.sub.3                                                                          COO(CH.sub.2).sub.2 S                                                                    ##STR30##         65/15/20            3  P-3                                                                              CH.sub.3                                                                           ##STR31##     H                                                                                  ##STR32##                                                                               ##STR33##         60/10/30            4  P-4                                                                              CH.sub.3                                                                           ##STR34##     CH.sub.3                                                                           ##STR35##                                                                               ##STR36##         65/10/25            5  P-5                                                                              C.sub.3 H.sub.7                                                                    ##STR37##     CH.sub.3                                                                           ##STR38##                                                                               ##STR39##         65/15/20            6  P-6                                                                              CH.sub.3                                                                           ##STR40##     CH.sub.3                                                                           ##STR41##                                                                               ##STR42##         50/20/30            7  P-7                                                                              C.sub.2 H.sub.5                                                                    ##STR43##     H   CONH(CH.sub.2).sub.2 S                                                                   ##STR44##         57/8/35             8  P-8                                                                              CH.sub.3                                                                           ##STR45##     H                                                                                  ##STR46##                                                                               ##STR47##         70/15/15            9  P-9                                                                              C.sub.2 H.sub.5                                                                    ##STR48##     CH.sub.3                                                                           ##STR49##                                                                               ##STR50##         70/10/20            __________________________________________________________________________

SYNTHESIS EXAMPLE 10 OF RESIN (P): (P-10)

A mixed solution of 60 g of 2,2,3,4,4,4-hexafluorobutyl methacrylate, 40g of a methyl methacrylate macromonomer (AA-6 manufactured by ToagoseiChemical Industry Co., Ltd.; Mw: 1×10⁴), and 200 g of benzotrifluoridewas heated to a temperature of 75° C. under nitrogen gas stream. To thesolution was added 1.0 g of AIBN, followed by reacting for 4 hours. Tothe mixture was further added 0.5 g of AIBN, and the reaction wascontinued for 4 hours. An Mw of the copolymer thus-obtained was 6.5×10⁴.

SYNTHESIS EXAMPLES 11 TO 12 OF RESIN (P): (P-11) TO (P-12)

Each of copolymers was synthesized in the same manner as in SynthesisExample 10 of Resin (P), except for replacing the monomer and themacromonomer used in Synthesis Example 10 of Resin (P) with each monomerand each macromonomer both corresponding to the polymer components shownin Table 6 below. An Mw of each of the resulting copolymers was in arange of from 4.5×10⁴ to 6.5×10⁴.

                                      TABLE 6                                     __________________________________________________________________________     ##STR51##                                                                    __________________________________________________________________________    Synthesis                                                                     Example of                                                                          Resin                                                                   Resin (P)                                                                           (P)                                                                              a   R              Y             b                                   __________________________________________________________________________    11    P-11                                                                             CH.sub.3                                                                          (CH.sub.2).sub.2 C.sub.n F.sub.2n+1                                                     n = 8 ˜ 1                                                                    --            CH.sub.3                            12    P-12                                                                             CH.sub.3                                                                          (CH.sub.2).sub.2 CF.sub.2 CFHCF.sub.3                                                         ##STR52##    H                                   __________________________________________________________________________    Synthesis                                                                     Example of                   x/y/z  p/g                                       Resin (P)                                                                              R' Z'               (weight ratio)                                                                       (weight ratio)                            __________________________________________________________________________    11       CH.sub.3                                                                          ##STR53##       70/0/30                                                                              70/30                                     12       CH.sub.3                                                                          ##STR54##       30/30/40                                                                             70/30                                     __________________________________________________________________________

SYNTHESIS EXAMPLE 13 OF RESIN (P): (P-13)

A mixed solution of 67 g of methyl methacrylate, 22 g of methylacrylate, 1 g of methacrylic acid, and 200 g of toluene was heated to atemperature of 80° C. under nitrogen gas stream. To the solution wasadded 10 g of Polymer Azobis Initiator (PI-1) having the structure shownbelow, followed by reacting for 8 hours. After completion of thereaction, the reaction mixture was poured into 1.5 l of methanol, andthe precipitate thus-deposited was collected and dried to obtain 75 g ofa copolymer having an Mw of 3×10⁴. ##STR55##

SYNTHESIS EXAMPLE 14 OF RESIN (P): (P-14)

A mixture of 50 g of ethyl methacrylate, 10 g of glycidyl methacrylate,and 4.8 g of benzyl N,N-diethyldithiocarbamate was sealed into acontainer under nitrogen gas stream and heated to a temperature of 50°C. The mixture was irradiated with light from a high-pressure mercurylamp of 400 W at a distance of 10 cm through a glass filter for 6 hoursto conduct photopolymerization. The reaction mixture was dissolved in100 g of tetrahydrofuran, and 40 g of Monomer (m-3) shown below wasadded thereto. After displacing the atmosphere with nitrogen, themixture was again irradiated with light for 10 hours. The reactionmixture obtained was reprecipitated in 1 l of methanol, and theprecipitate was collected and dried to obtain 73 g of a polymer havingan Mw of 4.8×10⁴. ##STR56##

SYNTHESIS EXAMPLES 15 TO 18 OF RESIN (P): (P-15) TO (P-18)

Each of copolymers shown in Table 7 below was prepared in the samemanner as in Synthesis Example 14 of Resin (P). An Mw of each of theresulting polymers was in a range of from 3.5×10⁴ to 6×10⁴.

                                      TABLE 7                                     __________________________________________________________________________    Synthesis                                                                     Example of                                                                          Resin                                                                   Resin (P)                                                                           (P)                                                                              A-B Type Block Copolymer (weight ratio)                              __________________________________________________________________________    15    P-15                                                                              ##STR57##                                                           16    P-16                                                                              ##STR58##                                                           17    P-17                                                                              ##STR59##                                                           18    P-18                                                                              ##STR60##                                                           __________________________________________________________________________

SYNTHESIS EXAMPLE 19 OF RESIN (P): (P-19)

A copolymer having an Mw of 4.5×10⁴ was prepared in the same manner asin Synthesis Example 14 of Resin (P), except for replacing benzylN,N-diethyldithiocarbamate used in Synthesis Example 14 of Resin (P)with 18 g of Initiator (I-11) having the structure shown below.##STR61##

SYNTHESIS EXAMPLE 20 OF RESIN (P): (P-20)

A mixed solution of 68 g of methyl methacrylate, 22 g of methylacrylate, 10 g of glycidyl methacrylate, 17.5 g of Initiator (I-12)having the structure shown below, and 150 g of tetrahydrofuran washeated to a temperature of 50° C. under nitrogen gas stream. Thesolution was irradiated with light from a high-pressure mercury lamp of400 W at a distance of 10 cm through a glass filter for 10 hours toconduct photopolymerization. The reaction mixture obtained wasreprecipitated in 1 l of methanol, and the precipitate was collected anddried to obtain 72 g of a polymer having an Mw of 4.0×10⁴.

A mixed solution of 70 g of the resulting polymer, 30 g of Monomer(M-1), and 100 g of tetrahydrofuran was heated to a temperature of 50°C. under nitrogen gas stream and irradiated with light under the sameconditions as above for 13 hours. The reaction mixture wasreprecipitated in 1.5 l of methanol, and the precipitate was collectedand dried to obtain 78 g of a copolymer having an Mw of 6×10⁴. ##STR62##

SYNTHESIS EXAMPLES 21 TO 25 OF RESIN (P): (P-21) TO (P-25)

In the same manner as in Synthesis Example 20 of Resin (P), except forreplacing 17.5 g of Initiator (I-12) used in Synthesis Example 20 g ofResin (P) with 0.031 mol of each of the initiators shown in Table 8below, each of the copolymers shown in Table 8 was obtained. A yieldthereof was in a range of from 70 to 80 g and an Mw thereof was in arange of from 4×10⁴ to 6×10⁴.

    TABLE 8      -      ##STR63##      SynthesisExample ofResin (P) Resin (P) Initiator (I) R      ##STR64##      21 P-21      ##STR65##      ##STR66##      ##STR67##     22 P-22      ##STR68##      ##STR69##      ##STR70##     23 P-23      ##STR71##      ##STR72##      ##STR73##     24 P-24      ##STR74##      ##STR75##      ##STR76##     25 P-25      ##STR77##      ##STR78##      ##STR79##

Synthesis Examples of Resin Grain (L):

SYNTHESIS EXAMPLE 1 OF RESIN GRAIN (L): (L-1)

A mixed solution of 40 g of Monomer (LM-1) having the structure shownbelow, 2 g of ethylene glycol dimethacrylate, 4.0 g of DispersionStabilizing Resin (LP-1) having the structure shown below, and 180 g ofmethyl ethyl ketone was heated to a temperature of 60° C. with stirringunder nitrogen gas stream. To the solution was added 0.3 g of AIVN,followed by reacting for 3 hours. To the reaction mixture was furtheradded 0.1 g of AIVN, and the reaction was continued for 4 hours. Aftercooling, the reaction mixture was passed through a nylon cloth of 200mesh to obtain a white dispersion. The average grain diameter of thelatex was 0.25 μm. The grain diameter was measured by CAPA-500manufactured by Horiba, Ltd. ##STR80##

SYNTHESIS EXAMPLE 2 OF RESIN GRAIN (L): (L-2)

A mixed solution of 5 g of AB-6 (a monofunctional macromonomercomprising a butyl acrylate unit, manufactured by Toagosei ChemicalIndustry Co., Ltd.) as a dispersion stabilizing resin and 140 g ofmethyl ethyl ketone was heated to a temperature of 60° C. under nitrogengas stream while stirring. To the solution was added dropwise a mixedsolution of 40 g of Monomer (LM-2) having the structure shown below, 1.5g of ethylene glycol diacrylate, 0.2 g of AIVN, and 40 g of methyl ethylketone over a period of one hour. After the addition, the reaction wascontinued for 2 hours. To the reaction mixture was further added 0.1 gof AIVN, followed by reacting for 3 hours to obtain a white dispersion.After cooling, the dispersion was passed through a nylon cloth of 200mesh. The average grain diameter of the dispersed resin grains was 0.35μm. ##STR81##

SYNTHESIS EXAMPLES 3 TO 6 OF RESIN GRAIN (L): (L-3) TO (L-6)

Each of resin grains was synthesized in the same manner as in SynthesisExample 1 of Resin Grain (L), except for replacing Monomer (LM-1),ethylene glycol dimethacrylate and methyl ethyl ketone used in SynthesisExample 1 of Resin Grain (L) with each of the compounds shown in Table 9below, respectively. An average grain diameter of each of the resultingresin grains was in a range of from 0.15 to 0.30 μm.

                                      TABLE 9                                     __________________________________________________________________________    Synthesis                                                                            Resin                                                                  Example of                                                                           Grain                Polyfunctional Monomer                                                                        Reaction                          Resin Grain (L)                                                                      (L)                                                                              Monomer (LM)      for Crosslinking                                                                         Amount                                                                             Solvent                           __________________________________________________________________________    3      L-3                                                                               ##STR82##                                                                                       ##STR83## 2.5 g                                                                               ##STR84##                        4      L-4                                                                               ##STR85##        Divinylbenzene                                                                             3 g                                                                               ##STR86##                        5      L-5                                                                               ##STR87##        --                                                                                             ##STR88##                        6      L-6                                                                               ##STR89##                                                                                       ##STR90## 2.5 g                                                                               ##STR91##                        __________________________________________________________________________

EXAMPLE 1

A mixture of 2 g of X-form metal-free phthalocyanine (manufactured byDainippon Ink and Chemicals, Inc.), 16 g of Binder Resin (B-1) havingthe structure shown below, 2 g of Binder Resin (B-2) having thestructure shown below, 0.15 g of Compound (A) having the structure shownbelow, and 80 g of tetrahydrofuran was put into a 500 ml-volume glasscontainer together with glass beads and dispersed in a paint shaker(manufactured by Toyo Seiki Seisakusho Co.) for 60 minutes. To thedispersion were further added 0.1 g of phthalic anhydride and 0.02 g ofo-chlorophenol, followed by dispersing for 5 minutes. The glass beadswere separated by filtration to prepare a dispersion for alight-sensitive layer. ##STR92##

The resulting dispersion was coated on an aluminium plate having athickness of 0.2 mm, which had been subjected to degrease treatment, bya wire bar, set to touch, and heated at 120° C. for 20 minutes to form alight-sensitive layer having a thickness of 8 μm.

Then, a surface layer for imparting releasability having a thickness of1.5 μm was provided on the light-sensitive layer.

Formation of Surface Layer for Imparting Releasability

A coating composition comprising 10 g of silicone resin having thestructure shown below, 1 g of crosslinking agent having the structureshown below, 0.1 g of platinum as a catalyst for crosslinking and 100 gof isoheptane was coated by a wire round rod, set to touch, and heatedat 120° C. for 10 minutes to form the surface layer having a thicknessof 1.5 μm. The adhesive strength of the surface of the resultinglight-sensitive element measured according to JIS Z 0237-1980 "Testingmethods of pressure sensitive adhesive tapes and sheets" was not morethan 1.0 g·f. ##STR93##

The above-described light-sensitive element having the surface ofreleasability was installed in an apparatus as shown in FIG. 6 as anelectrophotographic light-sensitive element. Transfer layer (X) wasformed according to the electrodeposition coating method while applyingDispersion of Resin (A) (L-1) having the composition shown below to thesurface of light-sensitive element using a device as shown in FIG. 6.

Dispersion of Resin (A) (L-1)

    ______________________________________                                        Dispersion of Resin Grain (A): (ARH-1)                                                             5 g                                                                           (solid basis)                                            Dispersion of Resin Grain (A): (ARL-1)                                                             5 g                                                                           (solid basis)                                            Charge Control Compound (D-1)                                                                        0.03 g                                                 (octadecyl vinyl ether/N-tert-octyl                                           maleic monoamide copolymer)                                                   Branched tetradecyl alcohol                                                                        10 g                                                     (FOC-1400 manufactured by Nissan                                              Chemical Industries, Ltd.)                                                    Isopar G             up to make 1 liter                                       ______________________________________                                    

Specifically, on the surface of light-sensitive element installed on adrum which was rotated at a circumferential speed of 150 mm/sec,Dispersion (L-1) described above was supplied using a slitelectrodeposition device, while putting the light-sensitive element toearth and applying an electric voltage of -120 V to an electrode of theslit electrodeposition device, whereby the resin grains wereelectrodeposited. The dispersion medium was removed by air-squeezingusing a suction/exhaust unit, and the resin grains were fused by apre-heating means of an infrared line heater at a temperature of 100° C.to form a film, whereby a transfer layer composed of a thermoplasticresin was prepared on the light-sensitive element. A thickness of thetransfer layer was 1.3 μm.

As a result of investigations on various characteristics of theelectrophotographic light-sensitive element having the transfer layerand that having no transfer layer, almost same results were obtainedalthough the former exhibited a residual potential 50 V higher than thelatter.

An electrophotographic process was then performed. Specifically, thelight-sensitive element 11 having the transfer layer (X) 12 providedthereon was charged to +550 V with a corona charger 18 in dark andimage-exposed to light using a semiconductor laser having an oscillationwavelength of 788 nm as an exposure device 19 at an irradiation dose onthe surface of the light-sensitive element of 30 erg/cm². The imageexposure was in a negative image mode based on digital image data on aninformation for yellow color separation among digital image data oninformations for yellow, magenta, cyan and black color separations whichhad been obtained by reading an original by a color scanner, conductingcolor separation and several corrections relating to color reproductionpeculiar to a system and stored in a hard disc.

Thereafter, the exposed light-sensitive element was subjected toreversal development using a liquid developer prepared by diluting apositively charged yellow liquid developer for Signature System(manufactured by Eastman Kodak Co.) with 75-fold by weight Isopar H(manufactured by Esso Standard Oil Co.) and supplied to a yellow liquiddeveloping unit 14y while a bias voltage of +350 V was applied to theyellow liquid developing unit 14y to thereby electrodeposit tonerparticles on the exposed areas. The light-sensitive element was thenrinsed in a bath of Isopar H alone to remove any stains in the non-imageareas, and dried by passing under a suction/exhaust unit 15 and apre-heating means 17a.

The above procedure was repeated using each information for magenta,cyan and black in place of the information for yellow to form colortoner images.

The light-sensitive element was then heated using the pre-heating means17a and a temperature controller 17 so as to maintain the surfacetemperature of light-sensitive element at 50° C.

Formation of Transfer Layer (Y) on Toner Image

Transfer layer (Y) was formed using Dispersion of Resin (A) (L-2) havingthe composition shown below in the same manner as the formation oftransfer layer (X) on the surface of light-sensitive element by theelectrodeposition coating method using Dispersion of Resin (A) (L-1)above.

Dispersion of Resin (A) (L-2)

    ______________________________________                                        Dispersion of Resin Grain (A): (ARL-2)                                                               10 g                                                                          (solid basis)                                          Charge Control Compound (D-1)                                                                         0.025 g                                               FOC-1400               10 g                                                   Isopar G               up to make 1 liter                                     ______________________________________                                    

By applying an electric voltage of -130 V to the electrophotographiclight-sensitive element bearing the toner image, the transfer layerhaving a thickness of 1.5 μm was formed.

Then, as a receiving material coated paper was superimposed on thelight-sensitive element 11 having the transfer layer formed on the tonerimages without cooling and they were brought into contact with a rubberroller for transfer, the surface temperature of which had been adjustedat 60° C. and subjected to heating and pressing under a nip pressure of4 Kgf/cm² and at a drum circumferential speed of 200 mm/sec, whereby thetoner images were wholly transferred together with the transfer layersonto the coated paper.

The duplicated images thus-formed on coated paper were visually observedtheir non-image areas and toner image areas using an optical microscopeof 200 magnifications. Background stain due to toner in the non-imagearea was not observed.

Also, the color toner images were wholly transferred onto the coatedpaper without remaining on the light-sensitive element, and theduplicated images were excellent without cutting or disorder of imagesof high definition such as fine lines or fine letters and cutting ordisorder of dots in highly accurate image portions such as half toneimages.

Further, duplications of color image were conducted using high qualitypaper, plane paper, copying paper for PPC, recycled paper for copyingand a PET film as receiving materials, respectively, in place of coatedpaper. On each of these receiving materials, duplicated images of goodimage quality similar to those on coated paper were obtained. The colorimages on the receiving materials had a sufficient strength since theywere covered with the transfer layer (X), and they did not fall off whenthey were rubbed and did not peel in case of filing in various filingsheets. Moreover, retouching and sealing properties of the duplicatesobtained were also good similar to those of plane paper.

The following comparative examples were conducted.

COMPARATIVE EXAMPLE 1

Color images were formed on coated paper in the same manner as inExample 1 of the present invention except for eliminating the formationof transfer layer (X) and transfer layer (Y). Partial cuttings of fineletters and fine lines were observed in the toner image areas on coatedpaper, and thus the duplicated image was poor.

Then, the transfer was conducted in the same manner as above except forchanging the transfer conditions of Example 1 to conditions of heatingand pressing and a transfer speed as described below. As a result, tonerimages were wholly transferred on coated paper and no residual toner wasobserved on the light-sensitive element. However, severe disorder ofimage on coated paper due to the occurrence of spreading or thinning offine lines and fine letters was observed.

Transfer Conditions

    ______________________________________                                        Temperature:         120° C.                                           Pressure:             10 Kgf/cm.sup.2                                         Transfer Speed:       2 mm/sec                                                ______________________________________                                    

COMPARATIVE EXAMPLE 2

Color images were formed on coated paper in the same manners as inExample 1 of the present invention except for eliminating the formationof transfer layer (Y). The transfer layer (X) and toner images wereincompletely transferred and the residue thereof was observed on thelight-sensitive element. Thus cuttings of toner images were formed inthe color duplicate formed on coated paper.

Then, the transfer was conducted in the same manner as above except forchanging the transfer conditions to those as described below. As aresult, the toner images and transfer layer (X) were wholly transferredonto coated paper and cutting or disorder of image was not observed. Acolor duplicate equivalent to one in Example 1 was obtained.

Transfer Conditions

    ______________________________________                                        Temperature:         90° C.                                            Pressure:             5 Kgf/cm.sup.2                                          Transfer Speed:      50 mm/sec                                                ______________________________________                                    

COMPARATIVE EXAMPLE 3

Color images were formed on coated paper in the same manners as inExample 1 of the present invention except for eliminating the formationof transfer layer (X). The result obtained was the same as that ofComparative Example 2 and specifically the transfer was incomplete.

Then, the transfer was conducted in the same manner as above except forchanging the transfer conditions to those as described below. A colorduplicate equivalent to one in Example 1 was obtained.

Transfer Conditions

    ______________________________________                                        Temperature:         80° C.                                            Pressure:             5 Kgf/cm.sup.2                                          Transfer Speed:       5 mm/sec                                                ______________________________________                                    

From these results it can be seen that the transfer conditions can bemoderated and the transfer speed can be increased according to themethod of the present invention. Moreover, rapid transfer can beperformed irrespective of the kind of a receiving material.

EXAMPLE 2

An amorphous silicon electrophotographic light-sensitive element(manufactured by KYOSERA Corp.) was installed in an apparatus as shownin FIG. 3.

Impartation of releasability to the light-sensitive element wasconducted by dipping the light-sensitive element in a solution of thecompound (S) according to the present invention (dip method) in theapparatus. Specifically, the light-sensitive element rotated at acircumferential speed of 10 mm/sec was brought into contact with a bathcontaining a solution prepared by dissolving 0.5 g of Compound (S-1)shown below in one liter of Isopar G (manufactured by Esso Standard OilCo.) for 7 seconds and dried using air-squeezing. The adhesive strengthof the surface of the light-sensitive element thus-treated was 3 g·f andthe light-sensitive element exhibited good releasability. ##STR94##

Then, transfer layer (X) was formed on the light-sensitive element inthe following manner.

An ethylene-vinyl acetate copolymer (content of vinyl acetate: 20% byweight; softening point measured by ring and ball method: 90° C.) wascoated as a thermoplastic resin for the transfer layer (X) on thesurface of light-sensitive element at a rate of 20 mm/sec by a hot meltcoater adjusted at 120° C. and cooled by blowing cool air from asuction/exhaust unit, followed by maintaining the surface temperature oflight-sensitive element at 30° C. A thickness of the transfer layerthus-formed was 2.0 μm.

The resulting electrophotographic light-sensitive material (hereinafter,simply referred to as light-sensitive material, sometimes) was chargedto +700 V with a corona discharge in a dark place and exposed to lightusing a semiconductor laser having an oscillation wavelength of 780 nmon the basis of digital image data on an information for yellow colorseparation among digital image data on informations for yellow, magenta,cyan and black color separations which had been obtained by reading anoriginal by a color scanner, conducting color separation and severalcorrections relating to color reproduction peculiar to a system andstored in a hard disc. The electric potential in the exposed area was+220 V while it was +600 V in the unexposed area.

The exposed light-sensitive material was pre-bathed with Isopar H(manufactured by Esso Standard Oil Co.) by a pre-bathing means installedin a developing unit and then subjected to reversal development bysupplying a liquid developer prepared by diluting a positively chargedyellow toner for an electrostatic color plotter (Versateck 3000manufactured by Xerox Corp.) with 50-fold Isopar H from the developingunit to the surface of light-sensitive material while applying a biasvoltage of +500 V to the developing unit side to thereby electrodepositeyellow toner particles on the unexposed areas. The light-sensitivematerial was then rinsed in a bath of Isopar H alone to remove stains inthe non-image areas and dried by a suction/exhaust unit.

The above procedure was repeated using each information for magenta,cyan and black in place of the information for yellow.

On the toner images thus-formed was formed transfer layer (Y) using anethylene-vinyl acetate copolymer in the same procedure described above.A thickness of the resulting transfer layer was 2.5 mμ.

Then, coated paper was superimposed on the light-sensitive materialbearing the color toner images and they were passed between a pair ofheating rubber rollers which were in contact with each other under apressure of 5 Kgf/cm² and whose surface temperature was constantlymaintained at 100° C. at a transportation speed of 100 mm/sec.

After cooling the sheets while being in contact with each other bypassing under a cooling roller, the coated paper was stripped from thelight-sensitive material whereby the toner images on the light-sensitivematerial were wholly heat-transferred together with the transfer layersonto the coated paper. Further, the toner images were completely coveredwith the thermoplastic resin of the transfer layer on the coated paperand thus they did not fall off when they were rubbed.

EXAMPLE 3

A mixture of 2 g of X-form metal-free phthalocyanine (manufactured byDainippon Ink. and Chemicals, inc.), 17 g of Binder Resin (B-3) havingthe structure shown below, 0.15 g of Compound (B) having the structureshown below, and 80 g of tetrahydrofuran was put into a 500 ml-volumeglass container together with glass beads and dispersed in a paintshaker (manufactured by Toyo Seiki Seisakusho Co.) for 60 minutes. Tothe dispersion were further added 3.2 g of Resin (P-2) described above,0.05 g of phthalic anhydride, and 0.002 g of o-chlorophenol, followed bydispersing for 2 minutes. The glass beads were separated by filtrationto prepare a dispersion for a light-sensitive layer. ##STR95##

The resulting dispersion was coated on an aluminum plate having athickness of 0.2 mm, which had been subjected to degrease treatment, bya wire bar, set to touch, and heated in a circulating oven at 120° C.for one hour to cure, whereby a light-sensitive layer having a thicknessof 8 μm was formed. The adhesion strength of the surface of theresulting electrophotographic light-sensitive element measured accordingto JIS Z 0237-1980 "Testing methods of pressure sensitive adhesive tapesand sheet" was 1 g·f.

For comparison, an electrophotographic light-sensitive element wasprepared in the same manner as described above except for eliminating3.2 g of Resin (P-2) according to the present invention. The adhesivestrength of the surface thereof was more than 400 g·f and did notexhibit releasability.

The light-sensitive element according to the present invention wasinstalled in an apparatus as shown in FIG. 4. Transfer layer (X) wasformed by the transfer method from release paper as shown in FIG. 4.

Specifically, on Separate Shi (manufactured by Oji Paper Co., Ltd.) asrelease paper, was coated a mixture of poly(vinyl acetate) having aglass transition point of 38° C. and poly(phenetyl methacrylate) havinga glass transition point of 50° C. (5:5 by weight) to prepare thetransfer layer having a thickness of 3 μm. The resulting paper wasbrought into contact with the light-sensitive element under thecondition of a pressure between rollers of 3 Kgf/cm², surfacetemperature of 60° C. and a transportation speed of 10 mm/sec, wherebythe transfer layer having a thickness of 3 μm was formed on the surfaceof light-sensitive element.

The resulting light-sensitive material was subjected to the formation ofcolor images in the same manner as in Example 1 and then transfer layer(Y) having a thickness of 3 μm was formed thereon in the same proceduredescribed above.

Transfer of the color toner images onto coated paper was performed inthe same manner as in Example 1 to form a color duplicate. The colorimages obtained on coated paper were good and free from stain and hadexcellent image strength similar to those in Example 1.

EXAMPLE 4

An amorphous silicon electrophotographic light-sensitive element(manufactured by KYOCERA Corp.) was installed in an apparatus as shownin FIG. 6. Impartation of releasability and formation of transfer layer(X) on the surface of light-sensitive element were simultaneouslyconducted in the following manner thereby providing the transfer layer(X).

On the surface of light-sensitive element installed on a drum, whosesurface temperature was adjusted to 50° C. and which was rotated at acircumferential speed of 10 mm/sec, Dispersion of Resin (A) (L-3) havingthe composition shown below was supplied using a slit electrodepositiondevice, while putting the light-sensitive element to earth and applyingan electric voltage of -130 V to an electrode of the slitelectrodeposition device, whereby the resin grains were electrodepositedand fixed. The transfer layer having a thickness of 1.5 μm was formed.

    ______________________________________                                        Dispersion of Resin (A) (L-3)                                                 ______________________________________                                        Resin Grain (AR-1)  8 g                                                                           (solid basis)                                             Charge Control Compound (D-2)                                                                     0.028 g                                                   having the structure shown below                                               ##STR96##                                                                    Compound (S-2)      1.0 g                                                      ##STR97##                                                                    Isopar G            up to make 1 liter                                        ______________________________________                                    

On the light-sensitive material obtained by the impartation ofreleasability and formation of transfer layer (X) on the surface oflight-sensitive element, color images were formed and transfer layer (Y)was provided thereon, then the color images were transferred onto coatedpaper in the same manner as in Example 2 to obtain a color duplicate.

The color images obtained were excellent because they were clear withoutthe formation of background stain and degradation of image quality washardly recognized as compared with the original.

EXAMPLE 5

A color duplicate was formed on coated paper in the same manner as inExample 2, except for replacing the means for imparting releasability tothe light-sensitive element with the method described below. Goodresults similar to those in Example 2 were obtained.

Specifically, a metering roll having a silicone rubber layer on thesurface thereof was brought into contact with a bath containing an oilof Compound (S-3) shown below on one side and with the light-sensitive.element on the other side and they were rotated at a circumferentialspeed of 15 mm/sec for 20 seconds. The adhesive strength of the surfaceof resulting light-sensitive element was 5 g·f. ##STR98##

Further, a transfer roll having a styrenebutadiene layer on the surfacethereof was placed between the metering roll dipped in the silicone oilbath of Compound (S-3) and the light-sensitive element, and thetreatment was conducted in the same manner as above. Good result similarto the above was obtained.

Moreover, in the above-described method using a metering roll/transferroll system, Compound (S-3) was supplied between the metering roll 121and the transfer roll 120 as shown in FIG. 7 and the treatment wasconducted in the same manner as above. Again, good result similar to theabove was obtained.

EXAMPLE 6

Color images were formed on coated paper in the same manner as inExample 2, except for replacing the means for imparting releasability tothe light-sensitive element with the following method.

Specifically, an AW-treated felt (material: wool having a thickness of15 mm and a width of 20 mm) impregnated uniformly with 2 g of Compound(S-5), i.e., dimethyl silicone oil KF-96L-2.0 (manufactured by Shin-EtsuSilicone Co., Ltd.) was pressed under a pressure of 200 g on thelight-sensitive element and the light-sensitive element was rotated at acircumferential speed of 20 mm/sec for 30 seconds. The adhesive strengthof the surface of light-sensitive element thus-treated was 6 g·f. Thefinal color images on coated paper thus-obtained were good similar tothose in Example 2.

EXAMPLE 7

Color images were formed on coated paper in the same manner as inExample 2, except for replacing the means for imparting releasability tothe light-sensitive element with the following method.

Specifically, a rubber roller having a heating means integrated thereinand covered with cloth impregnated with Compound (S-6), i.e.,fluorine-containing surface active agent (Sarflon S-141 manufactured byAsahi Glass Co., Ltd.) was heated to a surface temperature of 60° C.,then brought into contact with the light-sensitive element and they wererotated at a circumferential speed of 20 mm/sec for 30 seconds. Theadhesive strength of the surface of light-sensitive element thus-treatedwas 3 g·f. The final color images on coated paper thus-obtained weregood similar to those in Example 2.

EXAMPLE 8

Color images were formed on coated paper in the same manner as inExample 2, except for replacing the means for imparting releasability tothe light-sensitive element with the following method.

Specifically, a silicone rubber roller comprising a metal axis coveredwith silicone rubber (manufactured by Kinyosha K.K.) was pressed on thelight-sensitive element at a nip pressure of 600 g·f/cm² and rotated ata circumferential speed of 15 mm/sec for 10 seconds. The adhesivestrength of the surface of light-sensitive element thus-treated was 18g·f. The final color images on coated paper thus-obtained were goodsimilar to those in Example 2.

EXAMPLES 9 TO 26

Color duplicates were prepared in the same manner as in Example 1 exceptfor using each of the resin grains shown in Table 10 below in place ofeach of the resin grains (A) employed for the transfer layer (X) andtransfer layer (Y).

                  TABLE 10                                                        ______________________________________                                        Example    Transfer Layer (X) Transfer Layer (Y)                              ______________________________________                                         9         ARH-4   (100)    ARL-2   (100)                                     10         ARH-5    (50)    ARL-3   (100)                                                ARL-1    (50)                                                      11         AR-2    (100)    ARL-1   (100)                                     12         ARH-7   (100)    ARL-3   (100)                                     13         ARH-3    (60)    ARL-5   (100)                                                ARL-8    (40)                                                      14         AR-10   (100)    ARL-6   (100)                                     15         AR-9     (90)    ARL-15  (100)                                                ARL-15   (10)                                                      16         ARH-6    (40)    ARL-12  (100)                                                ARL-7    (60)                                                      17         ARH-8    (40)    ARL-16  (100)                                                ARL-3    (60)                                                      18         ARH-3    (50)    ARL-8   (100)                                                ARL-5    (50)                                                      19         ARH-1    (70)    ARL-9   (100)                                                ARL-12   (30)                                                      20         AR-3    (100)    ARL-10  (100)                                     21         AR-4    (100)    ARL-4   (100)                                     22         AR-5    (100)    ARL-11  (100)                                     23         ARH-3   (100)    ARL-13  (100)                                     24         ARH-1   (100)    ARL-2    (10)                                                                 ARL-14   (90)                                     25         ARH-9    (70)    ARL-1   (100                                                 ARL-12   (30)                                                      26         AR-3    (100)    ARL-3   (100)                                     ______________________________________                                         A weight ratio is indicated in ().                                       

The color images obtained on coated paper were clear duplicated imagesfree from background stain and had sufficient image strength. Further,the residue of transfer layer was not observed at all on the surface oflight-sensitive element after the transfer procedure.

Moreover, each of the coated paper obtained was held in a commerciallyavailable file made of vinyl chloride sheets, loaded with a weight of 1kg and stored under condition of 30° C. and 80% RH for one week tovisually evaluate the occurrence of transfer of the transfer layer andtoner images onto the vinyl chloride sheet. As a result, it was foundthat the color images did not peel and had excellent imagepreservability.

Furthermore, the color duplicates had good retouching property by apencil having hardness of HB or a ball-point pen of an aqueous type oran oily type and sealing property similar to those of plane paper.

EXAMPLES 27 TO 42

The procedure for the formation of transfer image same as in Example 2was repeated except that each of the resins shown in Table 11 below wasused in place of the ethylene-vinyl acetate copolymer for the transferlayer used in Example 2. Similar results to those in Example 2 wereobtained. A glass transition point of each resin shown in Table 11 wasin a range of from 20° C. to 80° C.

                  TABLE 11                                                        ______________________________________                                        Example    Resin                                                              ______________________________________                                        27         Cellulose Acetate Butyrate                                                    (Cellidor Bsp manufactured by Bayer AG)                            28         Polyvinyl Butyral Resin                                                       (S-Lec manufactured by Sekisui Chemical Co.,                                  Ltd.)                                                              29         Cellulose Propionate                                                          (Cellidoria manufacture Daicel Co., Ltd.)                          30         Polyvinyl Acetate                                                  31         Mixture of Vinyl Acetate/Crotonic Acid                                        (99/1 by weight) Copolymer and Cellidor Bsp                                   (8/2 by weight)                                                    32         Methyl Methacrylate/Methyl Acrylate                                           (60/40 by weight) Copolymer                                        33         Polypropyl Methacrylate                                            34         Mixture of Polyvinyl Methyl Ether and                                         Polyvinyl Acetate (5/5 by weight)                                  35         Styrene/Butadiene Copolymer                                        36         Styrene/Butadiene Copolymer                                                   (Sorprene 1204 manufactured by Asahi                                          Kasei Kogyo K.K.)                                                  37         Polydecamethylene Terephthalate                                    38         Polydecamethylene Isophthalate                                     39         Styrene/Vinyl Acetate (20/80 by weight)                                       Copolymer                                                          40         Polyhexamethylene Succinate                                        41         Poly-4-methylpentene-1                                             42         Polypentamethylene Carbonate                                       ______________________________________                                    

EXAMPLES 43 TO 49

Color images were formed on coated paper in the same manner as inExample 3 except that the formation of transfer layer was performed inthe following manner.

Formation of Transfer Layer

On release paper (Sanrelease manufactured by Sanyo-Kokusaku Pulp Co.,Ltd.) was provided a transfer layer having a thickness of 4 μm composedof each of the resins (A) shown in Table 12 below. The resulting paperwas installed in a heat transfer means 117 of a device shown in FIG. 5and the transfer layer was peeled from the release paper and transferredonto the surface of light-sensitive element under conditions of a nippressure of the rollers of 3 Kgf/cm², surface temperature of 80° C. anda transportation speed of 50 mm/sec. A glass transition point of eachresin shown in Table 12 was in a range of from 10° C. to 60° C.

                                      TABLE 12                                    __________________________________________________________________________    Example                                                                            Resin (A)                                                                __________________________________________________________________________    43   Mixture of Vinyl Acetate/Vinyl Butyrate (8/2 by weight) Copolymer             and Benzyl                                                                    Methacrylate/Methyl Methacrylate (8/2 by weight) Copolymer (60/40 by          weight)                                                                  44                                                                                  ##STR99##                                                               45                                                                                  ##STR100##                                                              46                                                                                  ##STR101##                                                              47   Mixture of Vinyl Acetate/Vinyl Propionate (7/3 by weight) Copolymer           and Evaflex ®                                                             420 (70/30 by weight)                                                    48   Mixture of                                                                     ##STR102##                                                                   and Polyvinyl Acetate (40/60 by weight)                                  49   Mixture of                                                                     ##STR103##                                                                   and Vinyl Acetate/Vinyl Butyrate/Crotonic Acid (82/15/3 by weight)            Copolymer (5/5 by weight)                                                __________________________________________________________________________

The color images obtained were clear and free from background stain, anddegradation of image quality was not substantially observed as comparedwith the original.

These results illustrate that in a case wherein a first transfer layer(X) is formed on the light-sensitive element using release paper and,after the formation of toner image, a second transfer layer (Y) isformed in the same manner as above thereon, then both transfer layersare transferred onto coated paper, the transfer layer is uniformly andcompletely transferred at each transfer step without any adverse effecton image quality.

EXAMPLE 50

5 g of 4,4'-bis(diethylamino)-2,2'-dimethyltriphenylmethane as anorganic photoconductive substance, 4 g of Binder Resin (B-4) having thestructure shown below, 0.8 g of Resin (P-3) described above, 40 mg ofDye (D-2) having the structure shown below, and 0.2 g of AnilideCompound (C) having the structure shown below as a chemical sensitizerwere dissolved in a mixed solvent of 30 ml of methylene chloride and 30ml of ethylene chloride to prepare a dispersion for light-sensitivelayer. ##STR104##

The resulting dispersion for light-sensitive layer was coated on aconductive transparent substrate composed of a 100 μm-thick polyethyleneterephthalate film having a deposited layer of indium oxide thereon(surface resistivity: 10³ Ω) by a wire round rod to prepare alight-sensitive element having an organic light-sensitive layer having athickness of about 4 μm.

Using the resulting light-sensitive element in place of thelight-sensitive element employed in Example 1, the same procedure as inExample 1 was repeated to prepare transferred images. The colorduplicated images obtained on coated paper were clear and free frombackground stain and the image strength thereof was also good.

EXAMPLE 51

A mixture of 3 g of X-form metal-free phthalocyanine (manufactured byDainippon Ink. and Chemicals, Inc.), 10 g of Binder Resin (B-5) havingthe structure shown below, and 80 g of tetrahydrofuran was put into a500 ml-volume glass container together with glass beads and dispersed ina paint shaker (manufactured by Toyo Seiki Seisakusho Co.) for 60minutes. The glass beads were separated by filtration to prepare adispersion for a light-sensitive layer.

The resulting- dispersion was coated on an aluminum substrate having athickness of 0.2 mm, which had been subjected to degrease treatment, bya wire bar, set to touch, and heated in a circulating oven at 110° C.for 30 minutes to form a light-sensitive layer having a thickness of 9μm. ##STR105##

In order to form an overcoat layer for imparting releasability on thesurface of light-sensitive layer, a solution having the compositionshown below was prepared.

Overcoat Solution

    ______________________________________                                        Overcoat Solution                                                             ______________________________________                                        Methyl methacrylate/glycidyl                                                                          3      g                                              methacrylate (80/20 by weight)                                                copolymer (Mw: 6 × 10.sup.4)                                            Resin (P-22)            0.5    g                                              Phthalic anhydride      25     mg                                             o-Chlorophenol          2      mg                                             Toluene                 100    g                                              ______________________________________                                    

The solution was coated on the light-sensitive layer with a wire bar ata dry thickness of 1.5 μm, dried in an oven at 100° C. for 20 secondsand then heated at 140° C. for 1 hour. The coated film was allowed tostand in a dark place at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive element.

The procedure same as in Example 1 was conducted except for using theresulting light-sensitive element in place of the light-sensitiveelement employed in Example 1 to prepare transferred images. The colorduplicated images obtained on coated paper were clear and free frombackground stain and had good image strength.

EXAMPLES 52 TO 62

Each light-sensitive element was prepared in the same manner as inExample 3 except for using each of the resins (P) and/or resin grains(L) and compounds for crosslinking shown in Table 13 below in place of1.5 g of Resin (P-2) and the compounds for crosslinking (i.e., phthalicanhydride and o-chlorophenol employed in Example 3.

                  TABLE 13                                                        ______________________________________                                               Resin (P)                                                                     or Resin                                                               Example                                                                              Grain (L)                                                                              Amount  Compound for Crosslinking                                                                    Amount                                 ______________________________________                                        52     P-18     1.8 g   Phthalic anhydride                                                                           0.2 g                                                          Zirconium acetylacetone                                                                      0.001 g                                53     P-22     3.0 g   Gluconic acid  0.008 g                                54     P-25     2.2 g   N-Methylaminopropanol                                                                        0.25 g                                                         Dibutyltin dilaurate                                                                         0.001 g                                55     P-9      3.0 g   N,N'-Dimethylamino-                                                                          0.3 g                                                          propanediamine                                        56     P-7      1.0 g   Propylene glycol                                                                             0.2 g                                         L-2      1.0 g   Tetrakis(2-ethylhexane-                                                                      0.008 g                                                        diolato)titanium                                      57     L-6      3.5 g    --                                                   58     L-1      2 g     N,N-Dimethylpropanediamine                                                                   0.25 g                                        P-24     3.2 g                                                         59     P-13     3.2 g   Divinyl adipate                                                                              0.3 g                                                          2,2'-Azobis(isobutyronitrile)                                                                0.001 g                                60     P-14     2.5 g   Propyltriethoxysilane                                                                        0.01 g                                 61     L-3      3.0 g   N,N-Diethylbutanediamine                                                                     0.3 g                                  62     P-5      4.0 g   Ethylene diglycidyl ether                                                                    0.2 g                                                          o-Chlorophenol 0.01 g                                 ______________________________________                                    

The same procedure as in Example 3 was conducted using each of theresulting light-sensitive element in a dark place to evaluate the imageforming performance and transferability. The color duplicated imagesobtained on coated paper were clear and free from background stain andthe image strength thereof was also good.

EXAMPLES 63 TO 68

Each color duplicate was prepared in the same manner as in Example 4except for using each of the compounds (S) shown in Table 14 below inplace of 1.0 g/l of Compound (S-2) employed in Example 4.

The results obtained were good and the same as those in Example 4.Specifically, the releasability is effectively imparted on the surfaceof light-sensitive element using the compound (S).

                                      TABLE 14                                    __________________________________________________________________________                                                    Amount                        Example  Compound (S) containing Fluorine and/or Silicon                                                                      (g/l)                         __________________________________________________________________________    63   (S-7)                                                                             Higher fatty acid-modified silicone (TSF 411 manufactured by                  Toshiba                                1.0                                    Silicone Co., Ltd.)                                                            ##STR106##                                                          64   (S-8)                                                                             Carboxy-modified silicone (X-22-3701E manufactured by Shin-Etsu               Silicone Co., Ltd.)                    0.5                                     ##STR107##                                                          65   (S-9)                                                                             Carbinol-modified silicone (X-22-176B manufactured by Shin-Etsu               Silicone Co. , Ltd.)                   1.0                                     ##STR108##                                                          66   (S-10)                                                                            Mercapto-modified silicone (X-22-167B manufactured by Shin-Etsu               Silicone Co., Ltd.)                    2                                       ##STR109##                                                          67   (S-11)                                                                             ##STR110##                            1.5                           68   (S-12)                                                                             ##STR111##                            2                             __________________________________________________________________________

EXAMPLE 69

A mixture of 5 g of a bisazo pigment having the structure shown below,95 g of tetrahydrofuran, and 5 g of a polyester resin (Vylon 200manufactured by Toyobo Co., Ltd.) was thoroughly pulverized in a ballmill. The mixture was added to 520 g of tetrahydrofuran with stirring.The resulting dispersion was coated on a conductive transparentsubstrate by a wire round rod to prepare a charge generating layerhaving a thickness of about 0.7 μm. ##STR112##

A mixed solution of 20 g of the hydrazone compound having the structureshown below, 20 g of a polycarbonate resin (Lexan 121 manufactured byGeneral Electric Co., Ltd.) and 160 g of tetrahydrofuran was coated onthe above-described charge generating layer by a wire round rod, driedat 60° C. for 30 seconds and then heated at 100° C. for 20 seconds toform a charge transporting layer having a thickness of about 18 μmwhereby an electrophotographic light-sensitive element having alight-sensitive layer of a double-layered structure was prepared.##STR113##

On the light-sensitive layer was formed a surface layer for impartingreleasabiiity.

Formation of Surface Layer for Imparting Releasability

A coating composition comprising 10 g of silicone resin having thestructure shown below, 1 g of crosslinking agent having the structureshown below, 0.2 g of crosslinking controller having the structure shownbelow, 0.1 g of platinum as a catalyst for crosslinking and 100 g ofisoheptane was coated by a wire round rod, set to touch, and heated at120° C. for 10 minutes to form the surface layer having a thickness of1.5 μm. ##STR114##

The adhesive strength of the surface of the resulting light-sensitiveelement measured according to JIS Z 0237-1980 "Testing methods ofpressure sensitive adhesive tapes and sheets" was not more than 1.0 g·f.

The formation of toner images and transfer of the images onto coatedpaper were conducted in the same manner as in Example 1 using theresulting light-sensitive element in place of the light-sensitiveelement employed in Example 1 to prepare a color duplicate. However,electric charging and light exposure to the light-sensitive element werecarried out in the following manner.

Specifically, the light-sensitive element 11 was charged to +500 V of asurface potential and exposed to light using a He--Ne laser having anoscillation wavelength of 633 nm at an irradiation dose on the surfaceof light-sensitive element of 30 erg/cm².

The color duplicate obtained had clear image free from background stain,and degradation of image quality was not substantially observed ascompared with the original.

POSSIBILITY OF UTILIZATION IN INDUSTRY

The method and apparatus according to the present invention can beeffectively employed for the formation of color images inelectrophotographic color duplicators, color printers, color proofers orcolor checkers, etc.

What is claimed is:
 1. A method of forming a color image comprisingforming at least one color toner image by an electrophotographic processon a first peelable transfer layer provided on the surface of anelectrophotographic light-sensitive element whose surface hasreleasability, forming a second transfer layer on the toner image andtransferring the toner image together with the first transfer layer andthe second transfer layer onto a receiving material.
 2. A method offorming a color image as claimed in claim 1, wherein the surface ofelectrophotographic light-sensitive element has an adhesive strengthmeasured according to JIS Z 0237-1980 "Testing methods of pressuresensitive adhesive tapes and sheets" of not more than 150 gram-force,before the formation of toner image.
 3. A method of forming a colorimage as claimed in claim 1, wherein the electrophotographiclight-sensitive element contains a polymer having a polymer componentcontaining at least one of a silicon atom and a fluorine atom in itssurface region adjacent to the first transfer layer.
 4. A method offorming a color image as claimed in claim 1, wherein theelectrophotographic light-sensitive element is caused by adsorption oradherence of a compound (S) containing at least a fluorine atom and/or asilicon atom onto its surface.
 5. A method of forming a color image asclaimed in claim 1, wherein the first transfer layer is formed by meansof electrodeposition or adhesion of resin grains (AR) by electrophoresison the surface of electrophotographic light-sensitive element to form afilm using a dispersion for electrodeposition comprising resin grains(AR) having a glass transition point of not more than 140° C. or asoftening point of not more than 180° C. dispersed in an electricallyinsulating organic solvent having a dielectric constant of not more than3.5 and at least one compound (S) which has a fluorine atom and/or asilicon atom and is soluble at least 0.01 g per 1.0 liter of the organicsolvent.
 6. An apparatus for forming a color image comprising a meansfor forming a first peelable transfer layer on the surface of anelectrophotographic light-sensitive element, a means for forming atleast one color toner image on the transfer layer by anelectrophotographic process, a means for forming a second peelabletransfer layer on the toner image formed on the first transfer layer anda means for transferring the toner image together with the firsttransfer layer and the second transfer layer onto a receiving material.